I just came here to suggest looking for sticks...or a loose wire/hose/hanger that may be rattling.....or even an acorn lodged in the muffler from a thrifty squirrel. I often get acorns and hickory nuts lodged in my fenders, exhaust, intake, etc. when I leave my truck parked somewhere for very long. A squirrel could have stashed a few when the truck was at the dealer or somewhere and it just started vibrating loose and now you hear it.....who knows?

 

You would have nailed it. In all my years ive never had that happen. That caused that kinda sound. I went to town last nite not a peep. Then this morning i thought What the heck is that.

I just hope that was it next cold morning ill know for sure .

 

Glad you found the problem. I was about to mention maybe some debris got lodged somewhere or some kid tied a long zip tie to the drive shaft.

 

The zip tie is about what it sounded like to the tee.