I am one of the guys Ezdub is talking about. I have had the pinion bearings go out. I bought a bunch from ready rollers for a $1 each. I redo my diffs every 2 or 3 weekends and swap out the bearings at that time, no big deal.
My car has atleast 3 gallons through it and thats the only problem I have had. No that I change those bearings often it wont be an issue. Also my car has zero slop.
If yours is a POS PM me I would like to have a practice buggy.