U-joints are a weak link in a drivetrain, the TTB has an extra, and lifting one requires a more expensive kit to drop everything to keep the geometry correct. Their limitation is exposed when tire selection comes up, but if you aren't trying to put it in the clouds on tractor tires they are perfect, the D50 TTB is only available in diesel applications I believe, 35" tires push it on them, and a heavier vehicle with that tire choice is going to break parts. I like them because you can get it under there without forcing you to raise the van way in the air, FYI a solid axle under an engine cradle designed for I-beams, even with the trimming, you are going to be pretty far up. When the TTB starts to fail is when people have put lockers in them and 38" tires, and start trying to rock climb. I traded tires to a guy, giving him my 35"x15.50" R15 TSL swampers, he put them on his TTB truck, then a Bronco with one, I don't recall him breaking anything, he played in the mud, it's loose, nothing to ****** the tire and cause it to require force to turn.
My wheelchair has yet to stop me from wrenching on my vans.