I realize this is a really old topic but one that comes up often. My brother SpeedHarrop
https://tinyurl.com/ytdhcsk4 is working on my rig to put the 27 gal. tank from his 1980 Toyota flatbed truck into my 1993 Dolphin. I encouraged him to join this group to document just how this is done.
https://tinyurl.com/ytdhcsk4