I called the truck driveshaft shaft shop which is local to me, from Japan, as I couldn't wait any longer. They said less then or about $200 to lengthen it 2", $80 for a tube piece and $120 for labor (2 cut, 2 welds, balancing). Will do some measurements when I get home to see if any of my front prop shaft can be used (tube diameter, flange ends, etc....). They may not accept used tube, or may not warranty it if used. Pricing did not include any yoke ends or U joints if needed. Still going to ask them about making the transition via adapter type U joint vs changing one/both of the ends.
A new "companion flange" output yoke for the trans is $300 by itself: https://www.finditparts.com/products/306076/fuller-86728-1 so will see if I can simply use the full round U joint yoke that is on there already. Used yoke ends appear to be around $100, if can find one.
or I could ship you the driveshaft from the truck that trans came from...