i was wondering if anyone knows what gear i would have in my car i have a 83 gt with a 7.5 i am swapping in a 8.8 out of a 90 gt. i was just wondering if anyone knows what gear is in the cra now and what normally came stock in a 90 gt.
Since you're swapping in the rear it's easy to check. Simply mark the driveshaft yoke, and the axle flange or hub. Then rotate the axle flange until the hub has turned exactly one rotation. Count the number of flange rotations - that's equal to your axle ratio. If it turns a little less than 2 and 3/4 times it's got a 2.73 in it; a little more than 3 and it's a 3.08; a little more than 3 and 3/4 and it's a 3.27; etc. You can do the same thing with your 7.5. Jack the back of the car up and count rotations between driveshaft and the rear tire. Unless you know the entire history of the car since new, relying on diff tags or the VIN information won't help. Many of these cars have had rearends or gear ratios changed.