I have a 86 GMC Jimmy 4x4 and i know it has 3:73 gear's that came from the factory, But how do i tell if it came with a posi rearend.
Supreme Member
1. Jack it up and spin the wheels. If they spin the same way, it's posi.
2. Look for a metal tag on the diff indicating: "Use Limited-Slip Type Lube Only"
2. Look for a metal tag on the diff indicating: "Use Limited-Slip Type Lube Only"
Supreme Member
Take off the cover and look. It's the only sure way to know.
If it has posi, it's probably the Eaton "Grenade-Lock".
If it has posi, it's probably the Eaton "Grenade-Lock".