this is what i found yesterday - after A YEAR of torturous irritating clunk coming from the passenger side rear end every time i hit a bump on the road.
can't tell you how many times i had scouted for the source, and even twice with truck on lift. nada.
anyhow, look at your rear leaf springs. 2nd from the bottom has plastic shim on either end. leaf is sticking off the 1st leaf about 8 inches?
i did it with my bare hand, you can do mallet if you want to. anyhow, tap that end UP! in my case, loud bang was produced very easily on both ends. nothing on the driver side - ????
i shimmed leafs. clunk is gone. drove yesterday, today, for about 100 miles.