Just wanted to post my experience with the 2020 Piston Caliper swap on a GMT800. My truck is a 2006 Z71.
The swap went pretty much flawlessly. I have seen a couple of topics on this swap on the web, but nothing on a gmt800 4wd.
ZERO modifications to the truck required ( with that being said I have 2015 Sierra 20" wheels, I doubt the stock 17" Z71 wheels will clear.) The only thing I had to do is get 4 washers, 2 for each side to center the caliper over the rotor, so the pads are not dragging on one side.
Even the screw that holds the rotor on at the factory fits in the same spot on the new rotors... lol.
Parts I used.
2019 - 2020 Silverado / Sierra 4 piston front calipers, rotors and pads.
CHECK your own clearances, I do not know if they vary truck to truck, these are what worked on mine.
The parts I got were a take off from a truck with around 5 miles on it... so the rotors and pads still required a little use to get them correct. Once I put them through a couple heat cycles, what a difference. I have yet to put new braided hoses I have. I wanted a fair comparison between the caliper swap. Hoping everything will keep working well with more miles put on them.... kind of a guinea pig here. LOL.