I doubt you will be breaking one of these rears. They put all sizes and types of engines in these trucks, deisels too, with higher torque. If you're gonna put in a big block or such, you won't get enough speed to hurt anything either.
ON the low oil, most I buy have been neglected there, and sounds like you'll need new seals on hubs and brakes now with leak mess. This is another area many old ones I dragged home were needing attention. Parking and setting does more harm than using on these trucks. Some people use synthetic lube now, wonder if you could do that? I have trouble believing that light stuff will lube safely compared to 90 wt. myself??
