Building an LS swap into your 2WD GMT400 OBS C1500? Speed Engineering's 1-7/8" LS swap longtube headers are specifically engineered for great fitment on the OBS platform — mandrel bent, TIG-welded, and CNC-machined for a precise fit on the most popular classic GM truck LS conversion. Compatible with the full LS engine family from 4.8L through 6.2L including LS1, LS2, LS3, LS6, and LSA. Dyno proven to deliver over 25 rear-wheel horsepower over stock manifolds.
Built from 304 natural stainless steel with merge spikes and standard graphite manifold gaskets included.
⚠️ Important Installation Notes:
- 2WD applications only — these headers will NOT fit 4WD C1500 trucks
- LS swap applications only — these headers are NOT compatible with standard SBC or BBC engines
- Due to older vehicle frame clearance, headers fit very tight and require Speed Engineering spark plug wires
- 4L80E or older Turbo 350/400 transmission — bellhousing ears may need to be trimmed for proper clearance
- Off-road X-pipe kit — requires a modified or aftermarket crossmember for proper fitment. Compatible with Suspension Engineering transmission crossmember with required shims (4L60 will need 3 shims)
Features:
- 1-7/8" Primary Tubes with Merge Spikes — Full-diameter flow from cylinder head to collector for maximum exhaust scavenging
- 3" Collector — Optimized for strong low-to-mid RPM torque
- Mandrel Bent Tubing — Consistent tube diameter through every bend; no crimping, no restriction
- CNC Machined Flanges — Precision fit at the cylinder head for a leak-free seal
- 304 Natural Stainless Steel Construction — Corrosion resistant, heat tolerant, and built to last
- Longtube Header Design — Maximum scavenging efficiency vs. shorty or mid-length headers
- Engineered for Great Fitment on the OBS Platform
- Standard Graphite Manifold Gaskets Included
- Dyno Proven — 25+ RWHP gain on LS applications
- Compatible with 4.8L, 5.3L, 6.0L, 6.2L, LS1, LS2, LS3, LS6, and LSA Engines
- LS V8 Engines Only
Vehicle Applications:
Note: All applications listed are LS swap conversions. 2WD applications only — will NOT fit 4WD trucks.
Chevrolet C1500 Truck (2WD) — GMT400 OBS
- 1988 Chevrolet C1500 Truck (2WD) — LS Swap
- 1989 Chevrolet C1500 Truck (2WD) — LS Swap
- 1990 Chevrolet C1500 Truck (2WD) — LS Swap
- 1991 Chevrolet C1500 Truck (2WD) — LS Swap
- 1992 Chevrolet C1500 Truck (2WD) — LS Swap
- 1993 Chevrolet C1500 Truck (2WD) — LS Swap
- 1994 Chevrolet C1500 Truck (2WD) — LS Swap
- 1995 Chevrolet C1500 Truck (2WD) — LS Swap
- 1996 Chevrolet C1500 Truck (2WD) — LS Swap
- 1997 Chevrolet C1500 Truck (2WD) — LS Swap
- 1998 Chevrolet C1500 Truck (2WD) — LS Swap
GMC C1500 Truck (2WD) — GMT400 OBS
- 1988 GMC C1500 Truck (2WD) — LS Swap
- 1989 GMC C1500 Truck (2WD) — LS Swap
- 1990 GMC C1500 Truck (2WD) — LS Swap
- 1991 GMC C1500 Truck (2WD) — LS Swap
- 1992 GMC C1500 Truck (2WD) — LS Swap
- 1993 GMC C1500 Truck (2WD) — LS Swap
- 1994 GMC C1500 Truck (2WD) — LS Swap
- 1995 GMC C1500 Truck (2WD) — LS Swap
- 1996 GMC C1500 Truck (2WD) — LS Swap
- 1997 GMC C1500 Truck (2WD) — LS Swap
- 1998 GMC C1500 Truck (2WD) — LS Swap
FAQ
Will these headers fit my 4WD C1500?
No. These headers are designed for 2WD C1500 applications only and will not fit 4WD trucks. For 4WD K1500 applications see part 25-1011 (1-7/8") or 25-1077 (2").
Will these headers work with my SBC or BBC engine?
No. These headers are designed for LS series engine swaps only and are not compatible with standard small block Chevy or big block Chevy engines.
Do I need special spark plug wires?
Yes. Due to tight frame clearance on older OBS truck platforms, Speed Engineering spark plug wires are required for proper fitment with these headers.
Does the off-road X-pipe kit bolt directly to the factory crossmember?
No. The off-road X-pipe kit requires a modified or aftermarket crossmember for proper fitment. The Suspension Engineering transmission crossmember is compatible with required shims — a 4L60 transmission will need 3 shims.
Will these fit with a 4L80E or older Turbo 350/400 transmission?
These headers may require trimming of the bellhousing ears on 4L80E or older Turbo 350/400 transmissions for proper clearance.
What LS engines are these headers compatible with?
These headers are compatible with GM LS V8 engines including 4.8L, 5.3L, 6.0L, 6.2L, LS1, LS2, LS3, LS6, and LSA.
How much horsepower do these headers add?
Speed Engineering's 1-7/8" LS swap longtube headers are dyno proven to add over 25 rear-wheel horsepower compared to stock exhaust manifolds on LS applications.
What material are these headers made from?
304 natural stainless steel with full TIG-welded construction, CNC-machined flanges, and merge spikes.
Are gaskets included?
Yes. Standard graphite manifold gaskets are included with the headers.
Are these headers street legal?
No. These are race-only headers intended for closed-course competition use only. Installation on a street-driven vehicle may violate the Clean Air Act (42 U.S.C. 7522(a)(3)).
⚠️ Race Use Only: This product is manufactured and sold for installation on vehicles used solely for competition. Once installed, the vehicle may not be used, registered, or licensed for use on a public road or highway. Installation on a street-driven vehicle may violate the Clean Air Act 203(a)(3), 42 U.S.C. 7522(a)(3).
