I have an 87 Cutlass Supreme 4-door. I am looking at changing my gears to get off the line faster. Now you guys are going to have to bare with me as I don't know a whole lot about what I currently have. All I know is that my gears now are in the 2.xx (43) i think. I want to put something in the 3.xx range possible 3.73. Can you help me out with what will fit in my diff without having to get a whole new rear end? Or what would be the best way to go about this?

Thanks

 

3.73 is nice, but only if you have an overdrive transmission. Does the 4-door have a TH-200 4R? If not, and if you spend any time on the highway, you'll be happier with something in the 3.08 - 3.23 range.

Your car probably has the "corporate" 7.5-inch rear end, which means there's an endless supply of aftermarket gears available. Find a rear-end shop that'll do the work for you, and ask them to determine which rear end you have. Swapping ring and pinion is not really something you want to do yourself anyway (requires special knowledge and tools).