I have a 86' N/A and have a few questions about the rear diff. First will an 89' rear diff fit in my car? Two what is your opinion on 4.375 final gear over my 4.1 final gear? Advantages and Disadvantages? Thanks

 

89 will fit, but only a VERY VERY few cars came with 4.3. But it'll fit fine, and it'll make a very slight improvement in acceleration..

PaulC