When should I go to a billet shaft. How much ft torque will snap a stock input shaft

 

I don't really have any idea but to be on the safe side I would say anytime you start increasing power. I don't think there is a definite # on torque to say when the shaft will snap. It's kinda like some of the others parts that some people can push beyond the limits and get away with it for a long time and others not so lucky

 

its not really the torque load that snaps the shaft its the hard lockup of a triple disk ive seen guys at stock power break thei inputs with a triple disk converter

 

If you think your going over 400hp then go billet. If you plan on doing any racing, sled pulling,long burnouts or boosted launching pretty much just using your truck for fun. Get the billet output as well.

You can make some stock shafts survive. Big ED on here has done some boosted launching and sled pulling along with many many long (pass out from the smoke) burnouts and his stock shafts are still spinning.