somewhere in my 109s life which if the cab is original to my frame started off as a gas auger truck, it acquired a detroit in the front diff and on ndt's it was manageable to steer but the wheel would would whip back straight at warp 9 once you were done turning, would pop a little but was dismissed as the clunks and bumps of the driveline binding in the turn, once i went to 395s it became near impossible to get more then 50% of the available steering range but cruising around in a field it would turn fairly ok with the reduced traction of grass/dirt. while servicing the hubs i suspected it may have something more then spider gears in the diff the way it reacted to spinning the axles and pinion by hand, i had to install locking hubs to make it driveable and then it was fine without the steering wheel whipping back to center, i confirmed the function of the diff by locking one hub and spinning that tire on the steep embankment behind my house, itll spin either side thats locked and drives ok on street with one hub unlocked to allow differential action
surprisingly they arent any more expensive then a pick up at under a g a pop, i kinda wanna move the whole detroit center section to the rear and put arb's in the center and front axles but that'll be a while before i drop 2g and that much effort