Option code X31 · Performance
Off-Road Suspension Package
GMC/Chevy off-road suspension bundle — twin-tube Rancho shocks, skid plates, dual exhaust on many years.
Documented on
- Sierra, Silverado
How to confirm it on a real car
GM RPO records factory equipment on the Service Parts Identification (SPID) label in the glovebox. Stickers go missing and cars get modified, so the ground truth for any specific VIN is the factory build record: every option code the car was born with, including X31 if it was ordered.
Was X31 on your car's original build?
The CarWhere build sheet decodes any GM VIN into its full factory record — every option code, the original paint, trim and equipment, as built. $9.99, instant.
More performance codes
Independent reference; not affiliated with GM RPO. Applicability varies by market and model year.