I'm using Tracy's RD-2C on my RX-8 powered RV-7A.  No problems with the gear drive.  I have 105 hours on the aircraft, engine and redrive.   I had a small oil leak in the cast redrive housing that had nothing to do with the redrive performance - Tracy replaced the housing and returned the redrive  to me - No Charge- and he would not let me pay  return shipping !! I'd only use Tracy's redrive on a rotary.

Dennis Haverlah