Am working on putting hydro assist on a friends 01 cummins. Is the box similar to the old chevy truck style box and same concept as how I tapped my 80s chevy box?

It's the same box as the 88-98 Chevy's IIRC. Find out what is needed for those, and you should be good to go. Sorry I can't help. I'm going to need to know quite soon aswell.

check these.. this is the box off my cruiser when i did it.. 3-bolt box of a 95 dodge pickup. same for chevy 88-up...

chris :cool2: