put in 8 3/4, now have vibration

Damn. I wish it wasnt you sayin this Badsport... because I have too much respect for your mopar knowledge... which means I will likely have to concede the problem is the short shaft and spend more money getting a new (used) one and pay to balance again...

But thanks for your input BadSport. The truth hurts sometimes, but I need it.

FYI It cost me $260.00 to have a brand new shaft built at my local shop.
This included new spicer ends and u-joints.
I just took them the slip yoke and gave them the measurements.