I just bought a parts car 87 or 88 RWD Cutlass Supreme, 307 engine and 4 speed auto 200-4R Trans. Has LIMITED SLIP LUBE TAG STILL ON ONE OF THE COVER BOLTS. What possible gear ratio is this?

 

Hi. There are a few possibilities. At the back diff cover, left side center, will be a flat spot on the axle housing itself. Look for a 3 didget code. First two will be 6B, for 7 1/2", 7k for 8 1/2" third will be another letter. Let me know the third letter, and I can figure your ratio. Let us know. Jim.

 

It's a 2.56