Ok I have this Rear Diff. I am not good at determining what ratio they are after they are removed. This one would in theory spin the driveshaft 4.5 times to one internal gear rotation. Does that mean its a 4.56 ratio? I want to make sure before I sell it to someone. It was exactly 4.5 rotations to one. THANK YOU!

 

sounds like a 4.56 to me. What did it come out of? If it came out of what you have in your avatar, and its a 3.0 auto, then its very likely 4.56:1

EDIT: I guess you can count the teeth on the pinion and on the ring and dvide the ring/pinioin.

 

Well I forgot what it came out of. I know it was a 86-95 4Runner but I cant recall exactly. Is that going to be an issue even if I figure out the gear ratio?(p.s my avatar photo is a 3rd gen so no 3.0L there)

 

divide the number of teeth on the ring gear by the number of teeth on the pinion gear

It's simple when you have it out

Count carefully

 

x3 on count the teeth, then divide

Here's the teeth count for the different ratios:
http://www.precisiongear.com/toy8v6.htm