Hey i picked up a 2000 XJ for $500 with a blown up D30 3.55 ratio low pinion, i want to replace it with one from a 1997 ZJ D30 3.55 low pinion thats at an auto wrecker fir a good price, The ZJ has a NP242 selec-trac and my XJ has a NP231 Command trac will the D30 from the ZJ work in my XJ i did some measuring on the mounts and it seems like it will bolt in. I know the best option would be to find a High pinion D30 to swap in but i cant seem to find one locally and im in a bind to get it up and running since im out of a vehicle atm any help would be great thanks!

I believe the ZJ, XJ, and TJ front axles are all interchangeable.

They are indeed interchangeable. The high pinion is much more desirable for strength, driveline angles and clearance. The low pinion will fit and work though. If the zj axle has cv axle shafts and the xj axle has u joint axle shafts I would keep the u joint axle shafts as they are stronger.

Yea i have been looking at every auto salvage around me but all i seem to find is the low pinion ones. Yea the ZJ axles are ujoints thankfully but appreciate the help and quick replies, now im just waiting for the auto wrecker to dig it out and pull the cover so i know if the gear set is not rusted out before i pay for it so i can get my jeep back on the road