They make spacer plates for these to make them work. It's basically a 2.5-3" chunk of aluminum that extends everything. Few guys on here in 4x4 section have done it, could probably find info pretty easy on gmfs. I know you can keep factory disc, or use drum off 14 bolts. You have to re-weld the spring perches OR put a wider plate on the axle, I've seen both ways. Re-welding is 'better' but the plate is much easier.