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The Walker SoundFX® 18133 universal muffler is built to deliver reliable performance, long service life, and OE-style acoustics for custom exhaust systems and replacement applications. Constructed from aluminized steel with durable mechanical joints, this muffler withstands thermal cycling and corrosion better than standard low-carbon steel alternatives.
Its universal design with a center inlet and dual offset outlets allows flexible adaptation to many full-size GM trucks from the late 1980s through the mid-1990s, as well as custom exhaust builds requiring a large-capacity oval muffler.
Corrosion-resistant aluminized steel for extended durability
Internal drainage system helps limit moisture buildup
Expandable bushings allow fitment flexibility for custom installations
OE-Style louvered tubes for factory-quality sound control
Mechanically joined tubes & spun-locked heads resist distortion
Premium construction enhances longevity compared to low-carbon steel mufflers
Quality-tested for sound, structure, and performance
| Specification | Value |
|---|---|
| Shape | Oval |
| Finish | Aluminized |
| Inlet Type | Pipe Connection |
| Outlet Type | Pipe Connection |
| Inlet Inside Diameter | 3.000 in |
| Outlet Inside Diameter | 2.250 in |
| Body Height | 4.250 in |
| Body Length | 23.000 in |
| Body Width | 9.750 in |
| Overall Length | 28.000 in |
| Inlet Location | Center |
| Outlet Location | Offset |
| Inlet Quantity | 1 |
| Outlet Quantity | 2 |
| Hanger Included | No |
| Reversible | No |
| Fitment Type | Universal |
| Body Material | Steel |
| Grade Type | Premium |
| Part Description | SoundFX Universal Muffler |
(Universal part — the following list reflects known compatible applications)
C1500 (1988–1993) — 5.7L V8, 6.2L V8
C2500 (1988–1995) — 4.3L V6, 5.7L V8, 6.2L V8 (C/J), 6.5L V8
C3500 (1988–1995) — 5.7L V8, 6.2L V8, 6.5L V8
K1500 (1988–1993) — 5.7L V8, 6.2L V8
K2500 (1988–1995) — 4.3L V6, 5.7L V8, 6.2L V8 (C/J), 6.5L V8
K3500 (1988–1995) — 5.7L V8, 6.2L V8, 6.5L V8
C1500 (1988–1993) — 5.7L V8, 6.2L V8
C2500 (1988–1995) — 4.3L V6, 5.7L V8, 6.2L V8 (C/J), 6.5L V8
C3500 (1988–1995) — 5.7L V8, 6.2L V8, 6.5L V8
K1500 (1988–1993) — 5.7L V8, 6.2L V8
K2500 (1988–1995) — 4.3L V6, 5.7L V8, 6.2L V8 (C/J), 6.5L V8
K3500 (1988–1995) — 5.7L V8, 6.2L V8, 6.5L V8
Universal muffler — requires cutting, fitment adjustment, and welding or custom adapters
Ensure alignment for center inlet → dual offset outlet configurations
No hangers included; installers must reuse or fabricate mounting hardware
Confirm inlet/outlet diameters match or adapt to existing piping
Professional installation recommended due to universal fit
Verify clearance around driveshaft, suspension, and heat-sensitive components
Recommended for GM full-size pickup exhaust repairs, custom systems, and retrofits
Not reversible — maintain inlet/outlet orientation for correct flow and sound
Order Processing
All orders are processed and shipped within 24 hours of purchase (excluding weekends and holidays).
Orders placed after 3:00 PM EST may ship the following business day.
Shipping Methods
Customers select their preferred shipping method and speed at checkout.
Shipping times are determined by the carrier and cannot be guaranteed by us.
Tracking information will be provided once your order has shipped.
Shipping Coverage
If your package arrives damaged, please notify the delivery driver immediately and contact the shipping carrier to file a claim.
You must report any missing or damaged items within 14 days of delivery.
After this time, we cannot be held responsible for lost or damaged items.
Return Window
You have 30 days from the date of delivery to request a return.
After 30 days, we are unable to accept returns, exchanges, or refund requests.
Eligibility
Items must be returned in their original condition—unused, unwashed, and with all tags and packaging intact.
Certain products may not be eligible for return (e.g., special-order items, customized products, or perishable goods).
Items that have been altered, installed, or modified cannot be returned.
Return Process
Contact our Customer Support team to request a Return Authorization (RMA) before sending items back.
Once your return is approved, you’ll receive instructions on where to send the product.
Customers are responsible for return shipping costs unless the item was defective or incorrect.
Refunds
Refunds are issued to the original payment method once the returned item has been received and inspected.
Please allow 5–10 business days for the refund to appear on your account.
In some cases, a restocking fee may apply (if applicable, this will be disclosed during your return authorization).
