dual tank idea

[Comet]

I don't know what your aux configuration looks like, but if it feeds from the top (like I think it does) then over pressurizing the pump would not be a problem. My concerns are leaks in your bottom fed in cab tank. Keep in mind you will need a rubber hose at some point in that line because the in cab tank is mounted to the cab, and the bed tank is mounted to the frame. They move separately. Eventually I fear the stress would cause a leak somewhere (even with a rubber fuel hose). Also, assuming you agree that a rubber hose is required, you would have at least 2 seams with fuel always in the line (at least when full). This just increases the chances of leaks. Be sure to double clamp it if you go that way.
The other concern is that you better use a new in cab tank or clean yours well. Bottom feeding will just pass the 30+ year gunk on to the next tank. Yes, if the bed tank is top fed, you will probably be ok, but you're still adding more stuff your filter needs to catch. I would put a small mesh screen between the two tanks, or a filter if you can find one big enough to fit the fuel hose between the tanks (I assume you are using large dia. hose between the tanks).

If you must go this route, I would top feed the in cab tank and use an electric fuel pump with a switch in the cab to supply the bed tank.

[jreb333]

i have no aux configuration of any kind right now. my truck has only one tank. i would definately clean both tanks before proceeding, the rubber hose joining the 2 tanks i agree is a must due to flexing. i dont want an aux set-up and i dont want to feed one tank into another with a slow electric pump however. i want to hop out of my truck at the pump, put 25-30 gals thru the stock fillerneck and drive away. a large capacity line gravity feeding is the only way i can come up with to accomplish this. ill definately have to use a regulator i never considered the pressure before.

[Comet]

I still don't think you need to worry about a pressure reg. The stock fuel pump pulls from the tank and if you pull it from the top you should be ok. How much capacity (total with both tanks) you trying to get? Keep in mind that some of these trucks have tanks as big as 25 gal. that have been added aftermarket. I don't think they had regs. on them.