Rear Diff Questions.

Identified my rear axle as the Chrysler 8.25 but now trying to decide if it is open, limited slip or has trac-lok. When i jack both rear wheels off the ground and spin one wheel forward the other wheel doesnt move at all. But when I spin that same wheel backward the opposite wheel spins forward. I'm assuming that this means I have an open diff but just trying to make sure before I change the diff fluid to determine if I need the friction modifier or not. And who in their right mind would order a Jeep with an open diff? Doesnt that kind of defeat the purpose of 4 wheel drive? I'm going to start looking at junk yards for limited slip and trac-lok axles so if anyone can tell me how to ID these items that would be greatly appreciated. Will a Dana 35 swap directly into the location vacated by the chrysler 8.25? Thanks. Steve

You are correct, it is an open diff. And yes, I'm sure that a D 35 rear end will bolt up, but you have to make sure that the gear ratio is the same as the one you are removing to work with the front diff. Your other option is to look at a locker, whether selectable or automatic.

One thing to keep in mind is that there are several lengths of rear drive shafts in XJ's. This depends on your transfercase and rear axle combo. Your current drive shaft my be fine for a dana35, but then again, it also may not.

Edit: Also, many many 4wd vehicles have open diffs. Some have limited slip and other addons, but most are open.