I posted the text of two of the recalls yesterday. See that thread here:
https://www.ford-trucks.com/forums/s...d.php?t=326043
Ford has had at least three designs. Generation 1 had the fuel selector valve. For the pickup trucks it was through about mid 1989. There was a recall on those.
Generation 2 got rid of the selector valve, using instead a "fuel delivery module" in each tank. The FDM has a high-pressure pump, a check valve and a shuttle valve. The check valve prevents backflow from the pressure side, the shuttle valve ensures that the fuel return line is only connected to the tank with the pump operating. In mid 1993 there was a different recall on generation 2. The fix then was to change out the regulator and add a redundant, external check valve in the pressure line coming from each pump.
Generation 3 would apply to your 1995 era truck. I believe this is the same as Generation 2, but not subject to the 1993 recall. Presumably it has an improved design Fuel Delivery module. It might have extra external check valves, as in the Gen 2 recall, though I doubt it.
If the check valve in the non-active tank leaks, there will be quite a bit of fuel transfer, because there is 40PSI worth of "head" on the pressure line. If the shuttle valve on the non-active tank leaks or sticks open, there can also be fuel transfer, though not as bad as with a leaking check valve, because there is less head.
If the shuttle valve in the ACTIVE tank sticks closed, it will create considerable back-pressure on the whole system. This may force fuel past the check valve or shuttle valve in the inactive tank. You should be able to tell that this is happening by the excessive fuel pressure evident at the fuel rail.
Chances are the problem lies in the rear tank. You have to replace the complete fuel delivery module. These are available at places other than Ford. It might be possible to add the redundant check valve, ala the 1993 recall, for less money. It is possible there is a recall on the later models, or that Ford would help you out, since it is a safety concern. I don't know, because I have a 1991.