2003 GMC Flowmaster Parts
Choose a Model for your 2003 GMC
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- Single; Single Side Exit; Includes 3.5 in. Tubing/50 Series(TM) Big Block Muffler/4 in. Logo Embossed Stainless Tip;50 State Legal / California Emissions Compliant Factory Dual Inlet Muffler Only
- American Thunder Cat Back Exhaust System; Single; Single Side Exit; Includes 3.5 in. Tubing/50 Series™ Big Block Muffler/4 in. Logo Embossed Stainless Tip;
- American Thunder Cat Back Exhaust System
- Product Attributes:
- Tip Quantity: 1
- Exhaust Type: Single
- California Proposition 65 Chemical Name 2: Chromium (hexavalent Compounds)
- California Proposition 65 Chemical Name 1: Nickel (metallic)
- Sound Level: Aggressive
- WARNING CA Proposition 65: Yes
- Exhaust Series: American Thunder
- Heat Shield Attached: No
- WARNING CA Proposition 65 Message: Warning: Cancer And Reproductive Harm - Www.p65warnings.ca.gov
- Exit Style: Straight
- Muffler Series: 50 Series Big Block
- Inlet Inside Diameter: N/a
- Exit Position: Single Side
- Muffler Count: 1
- Single or Dual: Single
- System Type: Cat Back
- Inlet Position: Dual
- Muffler Part Number: Kit Only
-
Features:
- Mandrel Bent 16ga Aluminized Tubing
- Moderate Exterior Exhaust Tone
- Includes Hangers And Hardware For Easy Installation
- Dyno Tuned for Maximum Performance
- Premium Flowmaster Quality
- 3 Year Limited Warranty
- Made in the USA
- For the person who wants a subtle custom appearance with all the benefits that a Flowmaster Cat-back exhaust system provides. This American Thunder system for the 2001-2006 (2007 Classic) Chevrolet Silverado, GMC Sierra 2500HD/3500HD with 6.0L or 8.1L engine with dual inlet muffler, delivers a moderate interior tone with a deep powerful exterior tone and is suited to the enthusiast who wants their performance to be heard. The system attaches to the back of the catalytic converter with a dual inlet 50 Series Big Block muffler for a deep powerful sound without being obnoxious. Includes a large custom formed aluminum heat shield with stainless clamps and easily attaches directly to the muffler body. The custom bent 3.50-inch aluminized steel tailpipe uses the factory hanger locations for an easy installation and exits out behind the right side rear wheel which is ideal for towing. The tailpipe is finished off with a large 4.00-inch polished 304 stainless steel tip embossed with the Flowmaster logo. Like all Flowmaster systems, the benefits include improved throttle response, power and mileage. Designed for an easy fit, these systems include all necessary parts, hardware and easy to follow instructions for a trouble free installation. Covered by our 3-year Limited Warranty. Check out system #817328 if you prefer a Stainless Steel exhaust system that is covered with a Lifetime Limited Warranty.
-
Suggested Purchase Quantity: 2
- Most jobs typically require 2 of this item.
This Part Fits the Following OEM/Substitute Numbers:
14294, 15789, 15829, 17800769, 39378, 615549, 817328
Additional Fitment Information:
| Vehicle | Block | CC | Engine | Bed Length | Sub Model | Body | CID |
|---|---|---|---|---|---|---|---|
| 2003 - GMC Sierra 2500 HD | V | - | 8 Cyl 8.1L | 78.0 | SLT | Extended Cab Pickup | 496 |
- Super 40™ Delta Flow Muffler
- 3.0 in. Offset Inlet/Offset Outlet; Case Dimensions 5 in. x 10 in. x 13.5 in.; 17.5 in. Overall Length; 409 Stainless Steel Not Direct Fit-Some Adaptation Required
- Super 40™ Delta Flow Muffler; 3.0 in. Offset Inlet/Offset Outlet; Case Dimensions 5 in. x 10 in. x 13.5 in.; 17.5 in. Overall Length; 409 Stainless Steel;
- Super 40(TM) Delta Flow Muffler
- Product Attributes:
- Tip Quantity: 0
- Automotive Item Grade: High Performance
- Mount Type: Uses New Hangers (not Included)
- Muffler Type: Reflection
- California Proposition 65 Chemical Name 2: Chromium (hexavalent Compounds)
- Outlet Connection Type: Pipe
- California Proposition 65 Chemical Name 1: Nickel (metallic)
- Outlet Position: Offset
- Sound Level: Aggressive
- WARNING CA Proposition 65: Yes
- Fitment: Universal
- Body Width: 10.000 In.
- WARNING CA Proposition 65 Message: Warning: Cancer And Reproductive Harm - Www.p65warnings.ca.gov
- Muffler Series: Super 40 Series
- Overall Length: 19.500 In.
- Shape: Oval
- Inlet Type: Single Offset
- Inlet Position: Offset
- Body Length: 13.500 In.
- Inlet Connection Type: Pipe
- Outlet Type: Single Offset Outlet
-
Features:
- Durable Fully Welded 16ga Stainless Steel
- Limited Lifetime Warranty
- Deep Aggressive to Moderate Exhaust Note
- Moderate Interior Resonance
- Excellent Performance On High Horsepower Vehicles
- Race Proven Patented Delta Flow® Technology
- No Internal Packing To Blowout
- Premium Flowmaster Quality
- Developed from our Top Ten race muffler lineup for use on the street/strip, the Super 40 features Flowmasters Delta Flow technology. Its larger case profile provides the best of both worlds of performance and sound, especially on forced induction and high horsepower vehicles. The Super 40 has that deep powerful sound of the Original 40 series but with all the benefits of performance and low interior resonance from the Delta Flow technology. Constructed of 16 gauge 409S stainless steel and fully MIG welded for maximum durability.
-
Suggested Purchase Quantity: 2
- Most jobs typically require 2 of this item.
This Part Fits the Following OEM/Substitute Numbers:
953048
Additional Fitment Information:
| Vehicle | Block | CC | Engine | CID |
|---|---|---|---|---|
| 2003 - GMC Sierra 3500 | V | 6599 | 8 Cyl 6.6L | 403 |
- Super 40™ Delta Flow Muffler
- 3.0 in. Center Inlet/Offset Outlet; Case Dimensions 5 in. x 10 in. x 13.5 in.; 19.5 in. Overall Length; Aluminized Steel
- Super 40™ Delta Flow Muffler; 3.0 in. Center Inlet/Offset Outlet; Case Dimensions 5 in. x 10 in. x 13.5 in.; 19.5 in. Overall Length; Aluminized Steel;
- Super 40(TM) Delta Flow Muffler
- Product Attributes:
- Tip Quantity: 0
- Outlet Position: Offset
- Sound Level: Aggressive
- WARNING CA Proposition 65: No
- Body Width: 10.000 In.
- Muffler Series: Super 40 Series
- Overall Length: 19.500 In.
- Shape: Oval
- Inlet Type: Single Center
- Inlet Position: Center
- Body Length: 13.500 In.
- Outlet Type: Single Offset Outlet
-
Features:
- Durable Fully Welded 16ga Aluminized Steel
- 3 Year Limited Warranty
- Deep Aggressive to Moderate Exhaust Note
- Moderate Interior Resonance
- Excellent Performance On High Horsepower Vehicles
- Race Proven Patented Delta Flow® Technology
- No Internal Packing To Blowout
- Premium Flowmaster Quality
- Noticeable Interior Resonance
- The Super 40 features Flowmasters Delta Flow technology. Its larger case profile provides the best of both worlds of performance and sound. The Super 40 has that deep powerful sound of the Original 40 series but with all the benefits of performance and low interior resonance from the Delta Flow technology. Constructed of 16 gauge aluminized steel and fully MIG welded for maximum durability.
-
Suggested Purchase Quantity: 2
- Most jobs typically require 2 of this item.
Additional Fitment Information:
| Vehicle | Block | CC | Engine | Sub Model | CID |
|---|---|---|---|---|---|
| 2003 - GMC Sierra 1500 | V | - | 8 Cyl 4.8L | SLE | 294 |
- 50 Series™ SUV Muffler
- 3.0 in. Center Inlet/Offset Outlet; Case Dimensions 5 in. x 10 in. x 17 in.; 23 in. Overall Length; Aluminized Steel Not Direct Fit-Some Adaptation Required
- 50 Series™ SUV Muffler; 3.0 in. Center Inlet/Offset Outlet; Case Dimensions 5 in. x 10 in. x 17 in.; 23 in. Overall Length; Aluminized Steel;
- 50 Series(TM) SUV Muffler
- Product Attributes:
- Tip Quantity: 0
- Automotive Item Grade: High Performance
- Mount Type: Uses New Hangers (not Included)
- Muffler Type: Reflection
- Outlet Connection Type: Pipe
- Outlet Position: Offset
- Sound Level: Mild
- WARNING CA Proposition 65: No
- Fitment: Universal
- Body Width: 10.000 In.
- Muffler Series: Super 50 Series
- Overall Length: 23.000 In.
- Shape: Oval
- Inlet Type: Single Center
- Inlet Position: Center
- Body Length: 17.000 In.
- Inlet Connection Type: Pipe
- Outlet Type: Single Offset Outlet
-
Features:
- Durable Fully Welded 16ga Aluminized Steel
- 3 Year Limited Warranty
- Mild to Moderate Exterior Exhaust Tone
- Minimal Interior Resonance
- Excellent Choice for Large Displacement Vehicles
- Improved HP/TQ and Potential Mileage Improvement
- Race Proven Patented Delta Flow® Technology
- Premium Flowmaster Quality
- The Super 50 series muffler is a larger version of Flowmasters 50 series Delta Flow muffler. Originally designed for trucks and SUVs, it is also well suited to muscle car and high performance applications. In addition, the larger case size significantly reduces interior resonance and provides a deep, rich tone along with mileage and power gains. Constructed of 16 gauge aluminized steel and fully MIG welded for maximum durability.
-
Suggested Purchase Quantity: 2
- Most jobs typically require 2 of this item.
Additional Fitment Information:
| Vehicle | Block | CC | Engine | Sub Model | CID |
|---|---|---|---|---|---|
| 2003 - GMC Sierra 1500 | V | 5328 | 8 Cyl 5.3L | SLE | 325 |
- 70 Series™ Big Block II Muffler
- 3.0 in. Center Inlet/Offset Outlet; Case Dimensions 5 in. x 10 in. x 22 in.; 28 in. Overall Length; Aluminized Steel Not Direct Fit-Some Adaptation Required
- 70 Series™ Big Block II Muffler; 3.0 in. Center Inlet/Offset Outlet; Case Dimensions 5 in. x 10 in. x 22 in.; 28 in. Overall Length; Aluminized Steel;
- 70 Series(TM) Big Block II Muffler
- Product Attributes:
- Tip Quantity: 0
- Automotive Item Grade: High Performance
- Mount Type: Uses New Hangers (not Included)
- Muffler Type: Reflection
- Outlet Connection Type: Pipe
- Outlet Position: Offset
- Sound Level: Mild
- WARNING CA Proposition 65: No
- Fitment: Universal
- Body Width: 10.000 In.
- Muffler Series: 70 Series Big Block
- Overall Length: 28.000 In.
- Shape: Oval
- Inlet Type: Single Center
- Inlet Position: Center
- Body Length: 22.000 In.
- Inlet Connection Type: Pipe
- Outlet Type: Single Offset Outlet
-
Features:
- Durable Fully Welded 16ga Aluminized Steel
- 3 Year Limited Warranty
- Stock to Mild Exterior Exhaust Tone
- Minimal Interior Resonance
- Recommended For SUV/Trucks/Motorhomes/Tow Vehicles
- Improved HP/TQ and Potential Mileage Improvement
- Race Proven Patented Delta Flow® Technology
- Premium Flowmaster Quality
- The 70 series utilizes Flowmasters Delta Flow technology and an enlarged case for improved sound control along with mileage and power gains. Perfect for use on trucks, SUVs, RVs, tow vehicles and high performance street cars where space allows. Constructed of 16 gauge aluminized steel and fully MIG welded for maximum durability.
-
Suggested Purchase Quantity: 2
- Most jobs typically require 2 of this item.
Additional Fitment Information:
| Vehicle | Block | CC | Engine | Sub Model | CID |
|---|---|---|---|---|---|
| 2003 - GMC Sierra 1500 | V | - | 8 Cyl 4.8L | SLE | 294 |
- 3.0 in. Dual Inlet/3.5 in. Offset Outlet; Case Dimensions 5 in. x 12 in. x 22 in.; 28 in. Overall Length; Aluminized Steel Not Direct Fit-Some Adaptation Required
- 50 Series™ Big Block Muffler; 3.0 in. Dual Inlet/3.5 in. Offset Outlet; Case Dimensions 5 in. x 12 in. x 22 in.; 28 in. Overall Length; Aluminized Steel;
- 50 Series™ Big Block Muffler
- Product Attributes:
- Tip Quantity: 0
- Automotive Item Grade: High Performance
- Mount Type: Uses New Hangers (not Included)
- Muffler Type: Reflection
- Outlet Connection Type: Pipe
- Outlet Position: Offset
- Sound Level: Mild
- WARNING CA Proposition 65: No
- Fitment: Universal
- Body Width: 12.000 In.
- Muffler Series: 50 Series Big Block
- Overall Length: 28.000 In.
- Shape: Oval
- Inlet Type: Dual
- Inlet Position: Dual
- Body Length: 22.000 In.
- Inlet Connection Type: Pipe
- Outlet Type: Single Offset Outlet
-
Features:
- Durable Fully Welded 16ga Aluminized Steel
- 3 Year Limited Warranty
- Stock to Mild Exterior Exhaust Tone
- Reduced Interior Resonance
- Improved HP/TQ and Potential Mileage Improvement
- Race Proven Patented Delta Flow® Technology
- Premium Flowmaster Quality
- Recommended For SUV/Trucks/Motorhomes/Tow Vehicles
- Minimal Interior Resonance
- The 50 Series Big Block muffler is made for more than just big cubic inch engine applications. Its large case size with internal tuning chamber provides mileage and power gains along with maximum sound control for a quiet interior tone, even under heavy loads. Well suited to heavy duty vehicles such as full size trucks, SUVs, RVs, and tow vehicles. Constructed of 16 gauge aluminized steel and fully MIG welded for maximum durability.
-
Suggested Purchase Quantity: 2
- Most jobs typically require 2 of this item.
Additional Fitment Information:
| Vehicle | Block | CC | Engine | CID |
|---|---|---|---|---|
| 2003 - GMC Sierra 2500 HD | V | - | 8 Cyl 8.1L | 496 |
- 3.5 in. Offset In; 3.5 in. Offset Out; 409 Stainless Steel; Moderate Sound
- 50 Series™ Heavy Duty Muffler; 3.5 in. Offset In; 3.5 in. Offset Out; 409 Stainless Steel; Moderate Sound;
- 50 Series™ Heavy Duty Muffler
- Product Attributes:
- Tip Quantity: 0
- Automotive Item Grade: High Performance
- Muffler Type: Reflection
- California Proposition 65 Chemical Name 2: Chromium (hexavalent Compounds)
- Outlet Connection Type: Pipe
- California Proposition 65 Chemical Name 1: Nickel (metallic)
- Outlet Position: Offset
- Sound Level: Moderate
- WARNING CA Proposition 65: Yes
- Fitment: Universal
- Body Width: 10.000 In.
- WARNING CA Proposition 65 Message: Warning: Cancer And Reproductive Harm - Www.p65warnings.ca.gov
- Muffler Series: 50 Series Hd
- Overall Length: 18.000 In.
- Shape: Oval
- Inlet Type: Single Offset
- Inlet Position: Offset
- Body Length: 18.000 In.
- Inlet Connection Type: Pipe
- Outlet Type: Single Offset Outlet
-
Features:
- Durable Fully Welded 409 Stainless Steel
- Limited Lifetime Warranty
- Moderate to Aggressive Exterior Exhaust Tone
- Reduced Interior Resonance
- Excellent Choice For Street Rods Cars and Trucks
- Improved HP/TQ and Potential Mileage Improvement
- Race Proven Patented Delta Flow® Technology
- Premium Flowmaster Quality
- Recommended for 6.2L Ford
- 6.4L Ram and 6.2L GM Trucks
- Mild Interior Resonance
- Flowmasters stainless steel 50 Series HD muffler is designed for todays heavy duty gas and diesel trucks. This muffler delivers improved performance, throttle response and mileage. The 50 HD features a deep, moderate tone with minimal interior resonance and is ideal for trucks with modified engines. This muffler is constructed of 409S Stainless Steel with a 3.5 in. inlet and outlet, and is covered by Flowmasters Lifetime Limited Warranty.
-
Suggested Purchase Quantity: 2
- Most jobs typically require 2 of this item.
Additional Fitment Information:
| Vehicle | Block | CC | Engine | CID |
|---|---|---|---|---|
| 2003 - GMC Sierra 2500 HD | V | 6599 | 8 Cyl 6.6L | 403 |
- Single; Dual Same Side Exit; Dual RH Before Rear Axle; Includes 2.5in. Tailpipes/Super 40 Series(TM) Muffler/3in. Embossed Stainless Tips;50 State Legal / California Emissions Compliant
- American Thunder Muscle Truck Exhaust System; Single; Dual Same Side Exit; Dual RH Before Rear Axle; Includes 2.5in. Tailpipes/Super 40 Series™ Muffler/3in. Embossed Stainless Tips;
- American Thunder Muscle Truck Exhaust System
- Product Attributes:
- Tip Quantity: 2
- Tubing Diameter: 2.500 In.
- Exhaust Type: Single
- California Proposition 65 Chemical Name 2: Chromium (hexavalent Compounds)
- California Proposition 65 Chemical Name 1: Nickel (metallic)
- Sound Level: Aggressive
- WARNING CA Proposition 65: Yes
- Exhaust Series: American Thunder
- Heat Shield Attached: No
- WARNING CA Proposition 65 Message: Warning: Cancer And Reproductive Harm - Www.p65warnings.ca.gov
- Exit Style: Straight
- Muffler Series: Super 40 Series
- Inlet Inside Diameter: 2.500 In.
- Outlet Outside Diameter: 2.500 In.
- Tail Pipe Diameter: 2.500 In.
- Exit Position: Dual Same Side
- Muffler Count: 1
- Single or Dual: Dual
- System Type: Cat Back
- Muffler Part Number: Kit Only
- Outlet Diameter: 2.500 In.
-
Features:
- Mandrel Bent 16ga Aluminized Tubing
- Aggressive Exterior Exhaust Tone
- Moderate to Aggressive Exterior Exhaust Tone
- Includes Hangers and Hardware For Easy Installation
- Connects After Factory Catalytic Converter
- Dual Out Same Side Exit
- Dyno Tuned for Maximum Performance
- Premium Flowmaster Quality
- For the person who wants the aggressive look of a NASCAR race truck along with all the benefits that a Flowmaster Cat-back exhaust system provides. D.O.S.S. (Dual out same side) systems are the perfect choice. The American Thunder systems deliver a moderate to aggressive interior and exterior tone and are suited to the enthusiast who wants their performance to be heard. The exhaust system is constructed from 3.00-inch mandrel-bent aluminized steel tubing flowing into a Super 40 Series performance muffler for a deep powerful sound, then is finished off with dual 2.50-inch tailpipes and a pair of 3.00-inch polished stainless steel tips. Includes all necessary hardware, instructions and is covered by our 3-year Limited Warranty. For those who prefer full stainless steel construction and a Lifetime Limited Warranty, check out part# 817395. Notes: Fits both 2/4 wheel drive models with extended cab/short bed configuration on a 143.5-inch wheelbase.
-
Suggested Purchase Quantity: 2
- Most jobs typically require 2 of this item.
This Part Fits the Following OEM/Substitute Numbers:
15842, 65518, 817395
Additional Fitment Information:
| Vehicle | Block | CC | Engine | Bed Length | Sub Model | Body | CID |
|---|---|---|---|---|---|---|---|
| 2003 - GMC Sierra 1500 | V | - | 8 Cyl 4.8L | 78.0 | SL | Extended Cab Pickup | 294 |
- 50 Series™ Big Block Muffler
- 3.0 in. Dual Inlet/3.5 in. Offset Outlet; Case Dimensions 5 in. x 12 in. x 22 in.; 28 in. Overall Length; Aluminized Steel Not Direct Fit-Some Adaptation Required
- 50 Series™ Big Block Muffler; 3.0 in. Dual Inlet/3.5 in. Offset Outlet; Case Dimensions 5 in. x 12 in. x 22 in.; 28 in. Overall Length; Aluminized Steel;
- 50 Series(TM) Big Block Muffler
- Product Attributes:
- Tip Quantity: 0
- Automotive Item Grade: High Performance
- Mount Type: Uses New Hangers (not Included)
- Muffler Type: Reflection
- Outlet Connection Type: Pipe
- Outlet Position: Offset
- Sound Level: Mild
- WARNING CA Proposition 65: No
- Fitment: Universal
- Body Width: 12.000 In.
- Muffler Series: 50 Series Big Block
- Overall Length: 28.000 In.
- Shape: Oval
- Inlet Type: Dual
- Inlet Position: Dual
- Body Length: 22.000 In.
- Inlet Connection Type: Pipe
- Outlet Type: Single Offset Outlet
-
Features:
- Durable Fully Welded 16ga Aluminized Steel
- 3 Year Limited Warranty
- Stock to Mild Exterior Exhaust Tone
- Reduced Interior Resonance
- Improved HP/TQ and Potential Mileage Improvement
- Race Proven Patented Delta Flow® Technology
- Premium Flowmaster Quality
- Recommended For SUV/Trucks/Motorhomes/Tow Vehicles
- Minimal Interior Resonance
- The 50 Series Big Block muffler is made for more than just big cubic inch engine applications. Its large case size with internal tuning chamber provides mileage and power gains along with maximum sound control for a quiet interior tone, even under heavy loads. Well suited to heavy duty vehicles such as full size trucks, SUVs, RVs, and tow vehicles. Constructed of 16 gauge aluminized steel and fully MIG welded for maximum durability.
-
Suggested Purchase Quantity: 2
- Most jobs typically require 2 of this item.
Additional Fitment Information:
| Vehicle | Block | CC | Engine | CID |
|---|---|---|---|---|
| 2003 - GMC Sierra 2500 HD | V | 5967 | 8 Cyl 6.0L | 364 |
- 50 Series™ Heavy Duty Muffler
- 3.5 in. Offset In; 3.5 in. Offset Out; 409 Stainless Steel; Moderate Sound
- 50 Series™ Heavy Duty Muffler; 3.5 in. Offset In; 3.5 in. Offset Out; 409 Stainless Steel; Moderate Sound;
- 50 Series(TM) Heavy Duty Muffler
- Product Attributes:
- Tip Quantity: 0
- Automotive Item Grade: High Performance
- Muffler Type: Reflection
- California Proposition 65 Chemical Name 2: Chromium (hexavalent Compounds)
- Outlet Connection Type: Pipe
- California Proposition 65 Chemical Name 1: Nickel (metallic)
- Outlet Position: Offset
- Sound Level: Moderate
- WARNING CA Proposition 65: Yes
- Fitment: Universal
- Body Width: 10.000 In.
- WARNING CA Proposition 65 Message: Warning: Cancer And Reproductive Harm - Www.p65warnings.ca.gov
- Muffler Series: 50 Series Hd
- Overall Length: 18.000 In.
- Shape: Oval
- Inlet Type: Single Offset
- Inlet Position: Offset
- Body Length: 18.000 In.
- Inlet Connection Type: Pipe
- Outlet Type: Single Offset Outlet
-
Features:
- Durable Fully Welded 409 Stainless Steel
- Limited Lifetime Warranty
- Moderate to Aggressive Exterior Exhaust Tone
- Reduced Interior Resonance
- Excellent Choice For Street Rods Cars and Trucks
- Improved HP/TQ and Potential Mileage Improvement
- Race Proven Patented Delta Flow® Technology
- Premium Flowmaster Quality
- Recommended for 6.2L Ford
- 6.4L Ram and 6.2L GM Trucks
- Mild Interior Resonance
- Flowmasters stainless steel 50 Series HD muffler is designed for todays heavy duty gas and diesel trucks. This muffler delivers improved performance, throttle response and mileage. The 50 HD features a deep, moderate tone with minimal interior resonance and is ideal for trucks with modified engines. This muffler is constructed of 409S Stainless Steel with a 3.5 in. inlet and outlet, and is covered by Flowmasters Lifetime Limited Warranty.
-
Suggested Purchase Quantity: 2
- Most jobs typically require 2 of this item.
Additional Fitment Information:
| Vehicle | Block | CC | Engine | CID |
|---|---|---|---|---|
| 2003 - GMC Sierra 2500 HD | V | 5967 | 8 Cyl 6.0L | 364 |
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