I blew out 3rd gear piston clutch in the 440-T4 right after the 4.9L engine upgrade (50% more torque than the original 4.1). Another guy that did a similar upgrade had the same problem. The cars that had the 4.9L were using the 4T60E with ~7 years of engineering upgrades, and the 4T65E is stronger still. Also the 440-T4 has no in-car serviceable parts, you must pull the engine and disassemble the trans to do anything to them, while the 4T6XE have removable side covers that allow for some in-car fixes. So it costs about $700 in shop time to drop a 440-T4 to fix or change something. Not having to fix stuff in the first place, and not having to pull the engine every time, pretty attractive upgrade.

And its fun, can I do this, not your everyday SBC 700R4 swap

strength i can understand. thats why i went with a th400 when i got my crate engine. and then a few months later when the stock rebuild failed. had to take it to a race shop but thats a different story.