yes, they do exist, but rare
BH is different, and also the torque converter (snout, where it fits into the crank) as well as the TCU
I'm running the 4.56 stock D30 from a 2.5/AW4 XJ in the front of my MJ, and another MJ friend of mine has a 2WD 2.5/AW4 MJ that I borrowed the rear D35 (4.56) out of until I regeared my D44 to match
edit: we converted my friend's MJ to 4WD, and he used a 4.0/XJ tranny, but had to swap the 2.5 BH and get a new torque converter (his old 2.5 one was leaking at the pump)....also had to fab up a trans mount