The easiest is to order the complete backing plate with new shoes already installed. Generally requires removal of 4 bolt and two wires to the magnet. Generally not much more that new shoes alone and much easier installation. I think they can be ordered directly from Dexter.
2018 Chevy 3500HD High Country Crew Cab DRW, D/A, 2016 Redwood 39MB, Dual AC, Fireplace, Sleep #Bed, Auto Sat Dish, Stack Washer/Dryer, Auto Level Sys, Disk Brakes, Onan Gen, 17.5" "H" tires, MORryde Pin & IS, Comfort Ride, Dual Awnings, Full Body Paint