F150 89 302 4x4

This noise just started today once the motor gets warm moving or just sitting at idle. It's a deep doming noise kinda like dddduuuuhhhmmmm haha that's pretty much what it sounds like. Seems to be coming from the back left of the motor( sitting in driver seat). Thanks for any help

 

Here is some more info. The truck is a 4spd with overdrive (so 5 spd?). When I crank the truck when it is warm it makes the noise rpms are about 1000 idling when it is making the noise used to drop to 700 idling. when it is making the noise if I push in the clutch it stops but within a few seconds it comes back and once I put it in gear and release the clutch it stops but comes back while going down the road.
Does what I explained make since?
Thanks
Rop3r