Right rear squeek?

I noticed a squeek when going over bumps coming from the right rear of my truck (2002 4wd 82,000 miles).
If I push on the rear bumper on that side, I can hear the squeeking, sounds like a bed would when it squeeks.

About 6 months ago I got new shocks(sorry, forget what kind).....just mentioning incase it matters.

Appears to only be coming from the right rear. Any ideas what would be causing the annoying squeek?

Try spraying some white lithium greese on the leaf spring bushings and in between the leafs and see if that helps.