Recently did this job - replaced the mounts and shackles. I got the replacement parts from Parts Geek. You'll need some air tools: a die grinder, cut off wheel, and air chisel to cut off the rivets of the old mounts and to pry those babies free. It's easier if you take the bed off and remove the gas tank. I did not; so it's still doable. I used the cut off wheel to make several close straight cuts (about 4 lines) across the head of the rivet. Then I used the air chisel (flat blade) to take off the rivet head. The die grinder cleaned up any of the head that was left. Then I used the air chisel with a pointed bit to knock out the rivet. Of course, you will first need to jack up the back, block up the axle and disconnect the leaf springs. The new mounts should bolt on where the old rivets were. I bought new shackles and, while I was there, I replaced all the bushings. Rides like a champ now - nice and quiet. I finished the whole job, including painting the frame under the old mounts in two weekends.