On the Willys Wagons and particularly pickups my thoughts are for clearance of the fuel tank and for a pto shaft to run out the back. I don’t remember the offset being a lot but It’s been quite a while since I looked under a stock one. As far as the later wagons and pickups I have no idea. Damage to other components caused by u-joint vibrations can happen. I’ve seen pinion bearings go bad and transfer case output bearings wiped out. Just out of curiosity, have you tried an offset driveshaft? If it were just to move the vehicle around a farm at low speed or something like that probably would be fine.