How to LS swap a OBS Chevy: parts list and steps

Chevrolet/GMC C1500 / K1500 "OBS" (1988–1998) LS swap: parts and gotchas from our sourced guides.

1988–1998 GM OBS C/K 1500/2500 LS swap: Dirty Dingo slider mounts (2WD/4WD), adjustable 2WD trans crossmember, AC brackets (PSI catalog).

Crossmember: PSI Conversion 88–98 Adjustable 2WD C1500/C2500 Automatic Transmission Crossmember ($244.99)

Mounts: Dirty Dingo DD-2550C 2WD LS Slider Engine Mounts; Dirty Dingo DD-2575-4 4WD LS Slider Engine Mounts

Accessory drive: Dirty Dingo DD-LS-R4-AC-TR LS R4 A/C Compressor Accessory Bracket (optional); Dirty Dingo DD-SANDEN-AC-TR LS Sanden A/C Compressor Accessory Bracket (optional)

Driveshaft: PSI Conversion Adapter to mate a 1350 U-joint yoke to a 3-bolt differential ($54) (optional)

Wiring/ECU: PSI Conversion 99–07 Gen 3 LS/Vortec (24X) Engine Controller Kit, drive-by-cable, w/ 4L60E-75/4L80E control (standalone harness, MAF, flashed ECM, bracket) ($1,099) (optional)

Watch out for: 2WD and 4WD use different mounts (Dirty Dingo DD-2550C vs DD-2575-4). OBS 3-bolt differential flange may need a 1350 U-joint yoke adapter. LT variants of the mounts exist.

More parts for this vehicle in our catalog (vendor listings, 2026 prices):

• Transmission Crossmember - 88-98 C1500 Silverado (ICT Billet, $200)
• Motor Mount Rubber - SBC 4wd 88-98 Chevy Truck (ICT Billet, $20)

See our engine, oil pan, transmission and wiring guides for choosing the rest of the combination.