When looking for a strange noise make sure everything is either removed or secured in the tail gate area.

I thought my drive shaft was going bad, then my rear axle, then my control arms, then my springs/shocks/trackbar. When I couldn't find anything loose I feared my differential was going.

Turns out it was my oil filter wrench banging in the rear seat well.

 

Amen sir. I put my trailer hitch in the area where the jack is supposed to go and It clunked like a mofo. I of course realized this after a thorough check and retourque of everything in the rear