Joining this as I want to do this as well. To me having to lower the tailgate and have the hose going in the bed is problematic to me.
One thing I thought of is the 47-48 factory under bed tank. But as I would like it on the drivers side and need an EFI setup, that tank is not ideal.
I had a 1995 ford F150 with two gas tanks (side between the frame rails and a rear tank), both having rubber hoses to the fuel doors in the side of body. If I could find something similar to that, which fits a 3100 short bed, it would be ideal. I should be able to use those aftermarket weld on fuel doors to go in the rear fender.
I like the 48 tank location but I have an explorer axle and the differential is shifted 2inches to the passenger side frame rail so clearance is an issue.
There is a person on a Facebook group that says a F150/250 tank from the mid 90s fits perfect with side fill but it looks that it might be a bit long front to back.
