Clunky Vibration.
 

I am getting a clunky vibration related to acceleration right underneath my driver's side floor pan. I had high speed vibration and I replaced the u-joints in my rear driveshaft and fixed that problem, but this clunking is still there. I am wondering if it would be the 4x4 driveshaft u-joint, the shaft does have a little slop in it. Is that play supposed to be there? Also wondering if a wheel bearing could cause that? I have a 2000 f150 4x4 5.4 extended cab. Thanks!

If you have the two part drive shaft in that one not sure of the years but on take off and slowing down you might feel a bump and that's the drive shaft needing greased.

It's not just when I take off or slow down, its whenever the truck is moving.