Keep an eye on the e-clips on the ends of the shafts, they have a tendency to dissapear. Also periodically check the tightness of the rear pivot block screws.(The big phillips heads on the bottom of the chassis in the rear)
Keep a supply of clutch bell bearings on hand.

Have you checked the slipper clutch?

The diff adjust screw is on the right side of the diff(passenger side). I'm not sure how far you will have to back it out...1/2 turn is the standard starting point, but you may have to change from that to compensate for wear, tolerances, tire selection, driving surface, driving style, prevailing solar winds, allignment of moons and stars, etc.

The way to test the diff to see if it is slipping is to set it on a bench and hold both rear tires. Now turn the spur gear with your thumb. First off...It should be hard to turn the spur, and make the driveline slip. Next, make sure that it is slipping in the slipper clutch.(the assembly that the spur is mounted to)
If the slipper is too loose, tighten it with the nut on a spring assembly sticking out the middle of the spur. Don't over-tighten this, as it is your stress relief for the drivetrain...every time you land off a jump or hop from a bump under throttle, it is like doing a neutral drop at WOT.[:@]