I am parting out a '94 Ford F-250. It looks like the rear tank on it will fit where my spare tire used to me. Can you say transfer tank? Double the fuel capacity baby! I think what I will do is just use the ford tank with stock fuel pump and level sender.
The sender I can wire up to a cheapo fuel gauge so I can watch how much fuel I have in it. The fuel pump I can wire up to a relay and put a switch in the bed, probably in my bed mounted battery box.
I can then vent the vent line on the Ford pump to atmosphere. Then take the pressure line and T it into the Toyota's vent line with a ball valve.
When the Toyota tank gets low, I park, open up the ball valve, and throw the switch for the Ford fuel tank. This will in turn fill the Toyota tank. One the Toyota tank is full, I turn off the switch and flip the ball valve. Done.
Only problems I have thought of so far is the filler neck is on the driver side, and filling the Toy tank will be guesswork as to when to stop unless I just unscrew the fuel cap and stop it when the fuel starts to come out.
Another way of running it would be to run the Ford pressure line into a fitting that screws into the drain bolt on the Toyota tank. I would still use a ball valve, but this way I don't have to mess with the toy vent line. The only drawback is if I ever whack the Toyota fuel tank on anything it will probably break off the Ford fuel inlet.
What do you guys think?