I swapped a 44 in place of an 8.25 and the driveshaft worked perfectly...
BUT
The 8.25 was not factory... the XJ was an 89. It had +3" approx AALs in the leafpacks.
The 44 had MORE spring perches (maybe +1" higher than factory 44 cast units) and at the same time I installed +6" leaf packs and MJ shackles.
I was able to re-use the driveshaft, and used a YJ slip-yoke for more swing before binding. Best I could tell, the yoke was sitting on the output shaft in approx the same location as before.
Also note that there may be several length factory driveshafts out there (to account for the various drivetrain combos.) I was looking at my spares the other day, and one rear shaft is a couple inches longer than the other.