Depends on what your working with. 2wd Duramax? Biggest killer is clearance. If a bag rubs on any metal, it's likely to fail on you. If you have plenty of clearance, than yes, with a little work, you can replace the coils with bags. Like on my first attempt, I just cleaned the lower control arm of anything related to the spring perch and made it nice and flat for a bag plate. Then you'll have to work the top mount. Most do what I did with a cup that goes into where the spring went. Then a plate. I'd suggest welding the top cup in but to be honest, a lot of guys float it. Basically the weight of the truck will keep it in place. I'd check out
www.streetsourcemag.com and see how other's do their trucks.