Putting an Explorer 8.8 rear in the XJ, It is under the XJ but have not welded the IRO perches on yet.
XJ has a ~3.5" lift.
with the 8.8 have the pinion offset a few inches, I have some questions.

I plan on a SYE, but have not decided on conventional U joints or a double cardan drive shaft, as I really don't want the pinion pointed up and possible pinion bearings running dry in DD.
If I did use a double cardan shaft and pointed the pinion up towards the trans, that would not help the fact that the pinion is offset and NOT pointed at the trans in the horizontal plane.
Would it make sense to do a conventional U joint set up, as the pinion would be parallel to the trans in the vert and horz planes?

Slack

 

Run the correct angle for your DS setup. I know allot of people running SYE's on there dailys in Wranglers with the rear diffs pointed way up with no issues with pinion bearings running dry.

 

the ring gear will spin the oil all over and lube your pinion bearing so pointing it up will not be an issues. i would recommend a SYE as you mentioned and a double cardigan. i don't have any vibs on mine with that set up and a 6" lift. you want to eliminate the vibs not only for comfort but anything vibrating causes stresses and will eventually lead to a failure.

 

Jon,
Thanks for the input,, yes vibes no matter how small will lead to failure.