Stall in stock 4L60e
Heat would be a concern and harmful over time, but can be controlled with an aftermarket cooler and reprogrammed fan settings (or an additional fan, if need be).
I think driving style and condition of the trans (prior to installing the converter) are the real factors of consideration in terms of trans life, not so much the converter itself.
A stock transmission, with all the leak points it's got, will eventually give way. Nothing lasts forever.
A high stall converter isn't going to kill a transmission that wasn't already on death-row to begin with.
Dana at Pro-built Automatics (PBA on this board) told me that the one thing that kills these trannies more than anything else is the super heavy high inertia stock converters. More to ponder.
Put a good cooler on that tranny with your hi-stall converter and it will last nearly forever. Finito.











