It occurs when I let off the clutch usually in 1st (just starting to roll) or in 2nd under the same circumstance. Sounds like it is coming from the pass. side but it may be dead center under the car. I have actually got it to occur when traveling slow in 2nd and hitting the gas. It doesn't happen every time, but enough to make me concerned. It does happen every day (3-4 as of now). Sounds like a metal clunk.

Transmission mount?

 

 

nipper

I was thinking it was a mount of some sort. Maybe a bushing for some suspension component? How do I test? - It would be wonderful if I could lay under the car while someone was driving.

I think you use a prybar and see if the trans has any freeplay/looseness near the mount? Some parts just a shakedown by hand will reveal looseness.