Update: I tore into the truck last night. It turns out that in addition to the loose clutch bellhousing, the inboard motor mount was no longer attached to the engine! These two problems had caused the nylon gears to strip, but I had spares in stock. I reassembled everything with loctite, and the truck was back in action. Back over to the construction site today, and got through three tanks of fuel before the truck was no longer able to move forward under it's own power.

Today's damage:

Broken right front diff cup. Both halves were completely sheared off, I guess that's what breaks after you reinforce the cup part.
(kept bashing)
The screw holding the bottom of the right rear strut at the bottom popped out, leaving that corner of the chassis dragging on the ground.
(kept bashing)
The right front tie rod end broke, leaving me with no steering control over that wheel.
(kept bashing, but started heading back towards the 1:1 car)
The steering control arm from the servo popped off, leaving me with no steering at all, ending the session.
(20 feet from 1:1 car, picked up the MT2 and carried it to the car)

The good news is, I'm not breaking the same stuff every time, so I have hopes that eventually I will have the car built up to the point where I can get through a whole session without anything breaking.