33's are pretty much the max on the stock Dana 35 rear axle on the XJ's too. I have a Super 35 kit in mine (30 spline axle shafts w/Detroit locker). Came off one of my parts rigs running 36" IROC's so I figure that it will hold up to my 33's with a heavy foot
. The Dana 30 up front is fairly tough though, I just have an OX selectable locker in there.
You do an axle swap with yours?