my neighbor asked if I could help him replace some parts.

I’ll start with saying I have not looked into this at all. it all started the other day when my neighbor was driving by my house. he stopped to chat and I noticed something hanging below his truck. It looked like it was a plastic skid plate over the gas tank. He brought it to a shop to have it looked at and they found that one of the straps holding his gas tank up had rusted through and failed. They replaced that but while they were under there, they said his rear end was leaking. They said either because of how it was leaking or how the thing is built, its easier (or he needs to) swap the whole rear end. I’m thinking just cut the leak spring brackets, disconnect the brake lines and drive shaft and the whole assembly should just roll out. Then swap any good parts from the old set up to the new and reattach everything. I also think that everything damn thing will be covered in rust and the whole job could just be an endless line of parts and swearing. I really havn’t looked up the truck to see what shape everything is in, but this is salt country, New England, I’m guessing its not good. (not actual truck but pretty close)