Rear End Gear identification

[DeputyDan]

can anyone tell me the best way to id what rear end gears I have in my truck. I'm assuming it's stock (72 Chevy Cheyenne Super) but have no idea what stock gears are. I looked under the truck today but couldn't find any numbers. Am I overlooking some type of id numbers somewhere? I am looking at upgrading to a 350 350hp 385tq and want to see if my current rear end will jive with that. Anyone have any suggestions?

[jakeblues652]

so theres 2 main options. either take the diff cover off, or theres a way you could jack it up and count the turns of the tire and drive shaft, but im not totally sure what that procedure is, but i bet someone would be glad to give you it!

[Sicklajoie]

Originally Posted by jakeblues652

so theres 2 main options. either take the diff cover off, or theres a way you could jack it up and count the turns of the tire and drive shaft, but im not totally sure what that procedure is, but i bet someone would be glad to give you it!

Mark the driveshaft. While turning the wheel one full revolution, count the number of times the driveshaft rotates and that's your ratio. A little over 4 driveshaft revolutions to one wheel revolution would be 4.11's.

[Tx Firefighter]

Originally Posted by Sicklajoie

Mark the driveshaft. While turning the wheel one full revolution, count the number of times the driveshaft rotates and that's your ratio. A little over 4 driveshaft revolutions to one wheel revolution would be 4.11's.

Assuming it's not posi, you have to turn the wheel 2 complete rotations and count the driveshaft revolutions.