I'm looking for a nice rear diff. cover for a 10 bolt 3.42 rear. Any suggestions where I could find one?

Summit has just about anything you could want for your car. I like the aluminum ones. Both of my brothers have one on their vehicles and they look really nice. They have the studs in them too which are supposed to help strenghen the rear a little (not sure if they actually do anything). You also dont have to worry about the covers leaking since they are about 1/2" thick aluminum they dont warp.

http://www.summitracing.com/search/D...?Ns=Rank%7cAsc

LPW ultimate rear covers are the best you can get,summits just a knock off of there cover

Next question is what size do I get? 7.5, 7.625, 8.2, 8.5, how do I know which to get?

7.5/7.625 are the same thing, and thats what you have