[RichardJ]

Used from a wrecking yard is fine. You will have to go to the yard to get the correct brackets anyway. The brackets are riveted to the frame, so take a good size chisel and hammer. A battery power drill with 1/4" bit would make the job go faster. Take note of where it is located, because you will see that you have to knock the rivets out of the lower side of your crossmember. Just put it all back together with new bolts.
You will find the larger bar on 3/4 or 1 Ton.
I thought the first one I put on my '67 was from a 3/4, but I found one from a '76 C30 and it was the 1 1/4" and looks a lot fatter and keeps the truck flatter on the corners.
NAPA had Blue urethane bushings in stock, but I don't remember the price. They may have had the stock bubber as well, but I don't remember that either.

I just now looked at the link passthebuck has posted. Tx firefighter explains what you will be doing a lot better and he has pictures. Be sure and look at that thread.