You are probably right. (YOU DID SAY YOU WERE LOOKING FOR THE KIND ON SEMIS...RIGHT
) All I know is I've been into trucking for 15 years now...and all I have seen is the fuel system with the crossover line at the bottom. The govt banned that system on trucks built after a certain date (I think the late 80s or early 90s). They went to the "dual feed dual return" system which is simply the fuel pump pumping fuel up to a tee valve from both tanks...going through the filter system to the engine and then returning it to an "equalizing splitter valve" and back to the tank. I do know that on some Freightliners and Peterbilts (I think), they have a couple of handles underneath the driver side door that are used to close a valve in the line. One go to the passenger side, the other for the driver side tank.
I looked at the Item mentioned on Ebay, If they used those on semis...I have never s