YEs diffs can be rebuilt, just look in your manual for the parts that need replacing, yes "up keep" can be a chore at times (even though i ejoy the wrench time), but try having 3 LST's like me (they get ran 4-5 times a week), i can now clean, check and fix most parts that need repair on all the trucks in about 2-3 hours on a saturday. Just takes a little practice. And if you arent enjoying it, i would say that nitro trucks are not for you.