Ok, I pulled the original 4WD unit from the NV4500 which was still in the truck to replace it with another unit I had, then realized that the other unit had been leaking (Black single wire hole) so I decided not to use it. On visual and touch examination of the output shaft of the NV4500, I could see and feel that the splines were worn down in a sine wave pattern. The original 4WD unit input shaft hole had the same, but the pattern was waves.
As nothing was really broken, I decided to shim the splines with two pieces of steel from two "tin" cans. I cut the first about 3/4 of the depth of the 4WD input shaft hole, and the second I cut just a little shorter than the depth, then flared it so the input shaft would go into it. I then aligned the cuts to 180 degrees and got the 4WD unit into position, held with a floor jack and the torsion bar suspension alignment bracket.
I then used one floor jack to lower and raise the engine and transmission and a second jack to lower and raise the transfer case, while I used to comalongs to press the output shaft into the input shaft hole making adjustments to obtain proper alignment by comparing the square of the mating surfaces to each other. After the cases were close enough I aligned the bolt holes and threaded the bolts into the transfer case. After there was sufficient threading I removed the comealongs and used the six bolts in a star pattern to pull the cases together. I then checked to see if anything had locked up or felt different from when I first started this and everything felt the same, not even any stiffness to indicate that I had jammed something.
That was as far as I got today, as it became to dark and cold to work, I will put in the transmission mount and bracket and the driveshaft tomorrow for a test drive, but I think it will be ok.
I dont plan on using this truck to tow anything off of my farm, so if it breaks down doing that again I havn't lost anything, and will put in a spare 4WD transmission that I have, but for now I am confident that I can drive it like a regular vehicle.
While I realize that this "fix" may not last forever, it gives me time to work on other vehicles.