The Chrysler 8.25" is a good axle, and there are factory limited slip diffs (Tracloc) out there if you wanted to search 'for sale' forums on the web. 3.55 is the most common, not a bad ratio. Could be worse, could be 3.07
Our '98 XJ had the exact same package, it also has an external tranny cooler from the factory. Be sure to tow in 3rd.