Sqeaking from rear. Need advice

[vess1]

I have been tuning in on this forum for a while now but this my first post.
I have a 2002 Quad cab that looks new other than a few door dings some idiots left for me. Anyway I have this squeaking when going slow over bad road or speed bump. I have basically bathed the rear of the undercarriage in WD40 and it won't stop. I pretty much come to the conclusion bushings are in order. My question is which ones should I zero in on short of replacing them all.

 

[SportRam00]

It might be your leaf springs. There are plastic inserts between each leaf that are supposed to stop them from squeaking. If they are worn out or missing, the springs will start to squeak a lot. Bushings could also be the culprit as well as they can start squeaking when worn.