I was pulling a trailer this past weekend and noticed the moaning noise everytime I accelrated from a stopped position. Could this be u-joints? It seemed to be worse with the increased load?

 

If I am at a stop position and accelerate I get a groan but only for a second as it is my weight shifting through the truck and the rear shackles are moving just a tad. You guys who have the sound only when starting to move try spraying the rear shackles with WD40 or PB Blaster and see what you get. Eventually you will need to pull them off and grease them if thats your issue.

 

I was pulling a loaded trailer the other day and noticed the moaning every time I accelerated from a stopped position. Could this be bad u-joints? Possibly making noises under load?