Weird rear squeak

I noticed a really strange squeak from the rear of my truck. I have the tsb leafs and not sure thats where the squeak is coming from. It only happens sometimes and I really only notice it when I hit a bump in the front and there the squeak is in the rear. The strangest thing is it doesn't happen if I go over speed bumps or anything like that. I can't seem to isolate it, maybe I've been drinking for too many years but I don't think I've lost it yet. Anyone else have an issue like this? I've read through the squeaky leaf section but seems to ba a little different. Thanks Jim

 

Mine did the same thing when I got thw tsb. Started as a squeak an after a year turned into a light rattle. Toyota didnt tighten the u bolts tight enough an two nuts were missing. Thought this hole time it was just squeaky leaf springs. Might not be your problem but I would check your u bolts an tighten them.

 

My u joint went out not to long ago it would squeak when I'd take off/hit bumps try checking your drive shaft...