Well the op has a 3906. I had one with a Novak HV and it was nothing but a headache munching on diffs and those skinny plastic sliders every other run.

The 3903/5/8 on the other hand is much improved and the trans is basically bulletproof. Also the diffs and plastic sliders will last with big power if you drive it right, but stop being nice and they'll give up pretty quick. I went 3 seasons with stock drivetrain and no issues powered by a Castle 1520 on 6s, just gotta watch the finger. Although the plastic sliders did oval out the holes for the universals, but they didn't break!