Thanks for the reply '248. Yeah, I really understand the "stocker" view point. That's how I am about my '65 GMC. I wanted to update the engine in the '56 and they threw the auto trans in the deal. Tell ya what, I'm learning a bunch.
I must have brain-farted earlier. The donor vehicle was a Chevy RV on a 1 Ton chassis, so the yoke on the tranny is the correct size to mate up to the existing driveline, but you are right, it will have to be shortened.
My daughters are pretty pi$$ed because I'm spending waaaay too much time in the garage but they did think it was pretty cool when I winched the old engine out.