My son bought a 90 F150 with the 6 cylinder (4.9L). It had been parked for years and we where told it was parked due to a bad fuel pump. We are in the process of replacing the fuel pumps and one of the tanks. My question is, do all F150's that have duel tanks have a selector value? We can not find the valve or any type of block on the truck anywhere in the fuel lines. I know it is supposed to be under the cab but it is not there. My thoughts are it was taken off and the lines plumbed together but it the lines don't look like they been hacked on.