To be fair, the Cup Car racers were having their gearboxes rebuilt at least once a season. The 'boxes were much younger/newer than they are now and were having a lot less power put through them than many of the tuned G40s about today - so they're bound to have faired better.
We all know the gearboxes aren't really capable of taking the torque many of our cars are putting out. Having said that, my box rattled within a few miles of JP rebuilding it - and they'd put the output flanges on the wrong side, so I won't go back there. Likewise, their cock-ups with the output flange nuts on Grippa LSDs are inexcusable.
