@chris the 4L80E is stout on its own, but like anything the more power you make the more likely you'll break something. I had mine built with a few extra clutches and such but its by no means crazy, and I think mine is holding up just fine. Just make sure you keep it cool. With a turbo I'd be more inclined to make sure you have a turbo spec'd converter, that might help longevity.

@casias the 241 isn't used in all gm 4wds, but most of the old ones. I dont know if the dodge ones are the same spline shafts or not. However, 07 and up silverados dont use the 4L80Es, as you found. Express vans do, but those are usually all 2wd. You could always have the trans rebuilt and change the output shaft.