on my truck if you push the clutch or let it out real quick in the lower gears it makes a loud clunking noise(especially in low) and was hoping someone might be able to help.I thought that it might be a Universal joint but they look fine to me.Any help would be appreciated.

 

I had an '84 Ranger (my first truck) that did that. It was caused from a few of the teeth on the pressure plate were broken. I guess the slave bearing slams on the shaft when it engages off-center. That may not be your problem, but it's a start.

 

Could this be caused by a mount? (more of a question than a statement)

 

I looked at the mounts and didnt see anything obvious.