Vibration Where It Shouldn’t Be

My truck seems to have developed a vibration the last few days, only happens when I’m idling down the road, not really speed dependent.

I got under the truck and started to check things out tonight and found that the front drive shaft moves a little when I shake it.
I’ve never really paid attention to it before but I’m guessing it’s not really supposed to have any movement.

Could this be my problem? Ujoint just went bad it is there something more to this?

(I’m not mechanic obviously)

 

What speed are you going when this happens? What kind of tires are you running? Checked air pressure lately?

 

35-50 mph, st Maxx’s, I have not. It feels like it’s right under my feet.

 

The front driveline shouldn't be coupled to wheels or transfer case. It will turn but usually at a lower speed. It's possible it could be a u-joint. Check the air pressure in the tires first. The tires can get cupping in them that will vibrate

 

But only when I’m off the gas?

 

Overlooked that part. Are you sure it's not an engine vibration. On or off gas shouldn't effect front drive shaft or front end.

 

Look at motor and trans mount really good.