How to tell what gear ratio your rear diff is?

[Soulprogression108]

My 94 has some wear in the driveline and rear diff. I just picked up a 95 for parts and the rear axle looks the same. I’m aware that the housing was but the diffs are typically different. I’m pondering swapping them since the 95 has 75,000 leas miles but I want to know how to find out the gear ratio without opening them up.

Is it in the vin? Or any other way to tell?

Anyone know if this would be a straight swap? Thank

 

[rdruss]

Get a rear wheel off the ground gear shift in neutral, put a chalk mark on your driveshaft lengthwise and one on the tire off the ground, then rotate the rear wheel by hand one revolution and count how many times the driveshaft rotates. The last revolution of the driveshaft will be less than one so estimate it as best you can, 3/4 turn = .75, half turn = .5, etc. My guess is it will be about 3-3/4 turns, so a 3.73 axle ratio.

 

[Hyde802]

Check out this great classic site to help you decode the tag to find out what diffs you have. (assuming they are stock)

Gearratiosanddiffs