I swapped a '96 HP axle into my '00 XJ replacing the LP that was in it. I didn't have ABS but other than that it was a complete "easy" bolt in replacement. I was told that somewhere around 95-96 and up all have the larger u-joints in the axles. I know the '96 axle I swapped in does.

The front DS from my LP axle fit perfectly with the HP axle.