Yeah the worst were the "1/2 and 1/2" (half SAE and half metric). Or when people assume that everything is metric.
The last trans my son sent in for a bench build (last one to that place as well, never again) a 4wd 727 no less, we sent it in with just enough bolts to hold the pan in place as we removed it upon removal to drain it..... It came back with a mix of 5/16 (which they are supposed to be) and M8 bolts holding the pan on... I ended up having to helicoil all but a few of them to stop it from leaking once it was reinstalled in his truck.
