Good evening all I know this has been talked about but I can't find it. I have a rear end to ID W Casting # 3856525 GM9 Code on top of axle HC 1129W E Internet says its a 1966 chevy truck with 3.73 Any help would be appreciated. Papy
You probably have it nailed from internet info but if it is a 1/2 ton 66 Chevy (not GMC) then it won't have any leaf spring perches welded on the axle tubes since they used coil springs on top of the trailing arms. Lock the axle/brake drum/wheel on one side and turn the axle/drum/wheel on the other side exactly TWO turns while counting how many times the pinion turns. If it turns very close to 3 and 3/4 turns it's a 3.73. The rare exceptions for Chevy to have leaf springs in a half ton were for models called "Camper Special" or "Heavy Half" which were just GMC rears in a Chevy.
Thanks Thanks Evan. It came with the truck. One place said it was a 69 posi and one off the casting number said 66. I'll take all parts to be replaced with me. Thanks again. Papy
If it is a posi then you can't turn just one wheel. If so, lift both wheels off the floor and either wheel ONE turn while counting how many times the pinion turns.
It's not a posi it is a 373 gear. Everything "looks"good except seals. Just don't trust half of what I read on the net. Thanks Papy
