My 2008 SD with 6speed manual makes a rattling sound whenever I accelerate or drive over. 60MPH. Anyone else have this problem, or know what is causing it?

 

I would check the u joints and center support bearing on the driveshaft if you have one, for play or slop. Also you could have a tire out of balance, or with a broken steel belt and the vibes are transferring up the drivetrain. Those would be the first places I'd check.

 

Thanks I believe I do have a tire out of balance as I get a vibration at 65 mph.