Aux fuel tanks: dealer installed? Worth keeping?

[Bill72]

As stated those are after market or dealer installed. The factory aux tank would be listed on the SPID with the code NL2 I believe. Valve on floor would be main and aux not main/R/L. Knob on left of dash to switch guage over to aux sender. Filler on factory tanks looks just like the cab tank and is located at the same height about 6 inches back on the bed. Since you were asking for opinions....
Get rid of it. Don't cut a good bed to mount those. Sell them to someone that wants them and if you want an aux tank mount it inside the frame where its safer.