XJ looks good. I'd say buy new quick disco's. You can buy them anywhere, I buy a lot of that stuff @ seriousoffroad.com. Good guy to deal with, I just bought new disco's yesterday (JKS is what I bought). They are adjustable from 3.5-6", so you can't go wrong.
SYE, if you have one the back of your transfer case will look like this:
The new (shiny) cap along with the new shaft (you can't see) eliminates the interior slip yoke & your drive shaft will be a spline shaft:
TC drop will be some box steel that is between your unibody & cross member that holds up your transfer case. Post picks & we can help you out.