Possible driveshaft rattle around 2500 rpm decelerating?

[DeusExMachina]

I have a bunch of track days coming up and I have this rattle that has been bugging me..

Deceleration around 2500 rpm from what sounds like the rear right I have this rattle, sounds like a heat shield but there aren't any heat shields back there obviously.

Any ideas? Should I replace the driveshaft ASAP? Its a bitch to get under there, there's no room and I can't see anything but I can move the driveshaft slightly around the middle if I shake it around.

Any input would be appreciated.