i think the tank won't have room in front of axle because of arms, it would too hard to run a hose from the orig filler location all way back to under bed due to cab and bed flexing, the in bed method will be in the way and prob the most dangerous because it's not protected at all and it gets rained on. you could prove me wrong though.
the bend in the hose will make it hard to go to fender on a fleetside bed and fill well. if it passes thru bed it will be in the way. it may be in the way anywhere you put it unless you leave it behind seat. not to talk you out out of it. i have the poly tank in my 64 and a steel tank in my 63. i prefer the steel, would prob prefer the aluminum if i had a fat wallet.
my 64 filler location in on side under a custom wrecker bed i made and it's a pain! you have to kneel down every time you get gas. the 63 is in the bed close to the drivers side , but it's a stepside. i don't like that a lot either, it is a little in the way but not bad. good luck, you may figure out a great solution. if so i may copy it!
