Odd Rumbling noise

[OpticsGuy]

I have a '96 Eddie Bauer Explorer 4X4 AT. When driving at speeds over 60mph, there is a rumbling noise from the driveline whenever I take my foot off of the accelerator. The noise is not present until I take my foot off of the gas. Any ideas?

 

[Nick26]

u joints getting loose? crawl under and try wiggling the rear drive shaft, if theres play in either of the joints it may be time for new ones.

 

[OpticsGuy]

u joints getting loose? crawl under and try wiggling the rear drive shaft, if theres play in either of the joints it may be time for new ones.

Yeah, I tried that, but everything in the drivetrain is tight enough that I can't move it by hand.