Welp...taking the nuts loose from the original tank filler is a no-go, at least until the solder is melted off of them. On a real close inspection of the original filler tube, it looks like there is a step in the tube (soldered slip joint) about 1/2" up the neck from the tank. It looks like the S-curve tube section actually solders INSIDE the straight stub filler of the new tank (after shortening it considerably).
To those that have removed the soldered on filler tube - a question:
Is the filler tube assembly a flanged pipe that bolts to the outside of the tank, then the whole flange is filled over with solder? That is what appears to be the case.
If I am going to have to have the filler modified, I would think it best to simply have the Rad shop swap the necks (after match-marking the tube for alignment) rather than cobble a union between the old and new.
I did speak with the vendor today (he called me) and he is sending some filler hose to try the "splice the old tube to the new neck idea", but I'm not sure I'm going to go that route as there is only about 2" between the tube and that body mount. The new tank's stub neck is about 3" long and the S-curve in the original start less than 3" from the tank. I need to sit under it and study it a bit more, but first - I gotta finish tuning the Jeep for the new temporary DD...
welcome to another day in the life........
Herb