[66-PMD-GMC]

The K member, (engine cross member?) that the suspension bolts to on the front end of that suburban bolts right to your 66 frame with 1 overall modification, you need to drill out 1 hole per side and elongate 1 hole per side after you bolt it to your trucks frame.
There are 14 bolts, 7 per side that bolt the entire suspension to the frame. It drops off in 1 complete unit.
Capfab makes a nice adaptor that will let you use the steering gearbox too giving you power steering.
If you have leafs the rear end is a direct bolt in. If you have trailing arms you can weld perches on the 'burbs rear housing as it is probably a better gear.
(66 was commonly 3.73 or 4.11)
Take a look at my build and the rear and front suspension is from a 79 and I have several other things I found will help.