Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1991 GMC Forward Control 5.7 K, Standard, SM465/M20FACTORY OEM SERVICE PROCEDURE
Body Code Designations (Trucks & Vans)
BODY CODE DESIGNATIONS (GENERAL MOTORS TRUCKS & VANS)
| Model | (1) Designation | |||
|---|---|---|---|---|
| Astro & Safari | ||||
| 2WD | "M" Series | |||
| 4WD | "L" Series | |||
| Blazer, Jimmy, Pickup & Suburban | ||||
| 2WD Models | "C" & "R" Series | |||
| 4WD Models | "K" & "V" Series | |||
| Pickups, Sonoma | ||||
| 2WD | "S" Series | |||
| 4WD | "T" Series | |||
| Van | "G" & "P" Series | |||
|
||||
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.