I had to buy the combo joint for my shortened XJ shaft. Luckily though i read that on another forum, so i didn't have any down time. I plan to swap to an 8.8 also sometime in the future also (keeping an eye out locally, missed a 4.88 geared 8.8 with lsd for 300 2 months ago...), so i didn't want to spend the money on a 1310 u joint dana 35 yoke to go to regular 1310 u joints...