I had this happen the other day and again yesterday. With 240 gallons of Diesel in the bed, I was a little heavy but not over loaded. Every dip and bump I hit came with a loud Clunk from the rear suspension. Not knowing much about Dodge suspensions, I see a stop perch(??) for the upper set of springs. Could the springs hitting this be the sound?

 

I have an 89 CTD cab and chassis with a "noise" too. It turned out to be "U" joint. I replaced the two on rear drive shaft. All better now. Hope yours is as easy too.

 

I t is probably the overload springs hitting on the pad when you hit a bump. Mine does it sometimes also.

 

my rear sway bar end links did that until i replaced them.

 

I had this happen to me on my old '97. The rear leaf spring shackle rusted through and broke and the rear leaf spring end slammed up against the underside of the truck bed.

 

Sounds like I need to just get my lazy *** under the truck this weekend.