How to identify rearend ratio in 83 C10?

[galong05]

Guys,

Just had a new 383 stroker installed in my 83C10; still seating the rings, so haven't hammered it down yet to see if I am satisfied with my rear end ratio.  Can someone tell me how to identify the rear end ratio in the 83 C10? It was originally a 305 v8 with 700r4.

[zieg85]

Easiest is if the sticker is still inside on the glovebox door.  Most accurate is to pull the rear cover off the diff and rotate the ring gear around until you see the numbers on it, divide and there it is...

[Stewart G Griffin]

The SPID sticker might also be on the left inner fenderwell.   There will codes listed and each code corresponds to a certain ratio based on if 1/2, 3/4 or 1 ton etc.

[Elpresidente]

That or just jack up the rear end, and have someone spin the tires one complete turn while you count the pinion rotations, then kind of rough it out from there. Not accurate, but it works.

[Captkaos]

With this amount of age, I wouldn't trust the options sheet.  How may here have changed the rearend?