Glad you figured that out. It will vibrate more, but not much if driveshaft is balanced. Mine stopped vibrating after swap to alum one.
It's good to know what my stock '96 V6 tranny mount looks like Never seen anything like this

 

So do you think I can get rid of a lot of that vibration if I swap my two piece drive shaft to a one piece? Anyone know what the part number for the aluminum one piece drive shaft and will it fit right in place of the 2 piece with out any problem?

 

Look in for-sale sections or on ebay. Any LS1, 1LE alum one will fit. Should have good U-Joints and balanced. Something around $100-$130. very nice upgrade over stock.

 

Thanks!