The transmission ended up being a '96 GM trans. This meant that it had the Dodge bellhousing to transmission pattern and the 5.61 granny and reverse. After weighing my options for installation,
http://67-72chevytrucks.com/vboard/s...01#post6424301
I decided to go with an adapter plate. The first step was to come up with a Dodge gas input shaft and bearing retainer ($100 shaft, $50 retainer courtesy of the best transmission shop in town). This input shaft is 1" longer than the GM and has the same spline count and shaft width (10 spline 1.125"); however, the pilot shaft is .75" instead of the .59" that the GM shaft has. Using this shaft will allow me to mount a 1" thich adapter between the bellhousing and transmission.
The first pic shows the Dodge gas shaft on the left and the GM shaft that came out of the tranny on the right. I swapped the front bearing to the new shaft and installed it and the new bearing retainer on my trans to end up with the bottom pic (yeah, I didn't clean up the transmission).