so, I have one of the 22 gallon man-a-fre rear auxillary gas tanks under the rear tub on my FJ. works great. BUT..... I cannot seem to find out the answer (man-a-fre website does not have it listed from what I can see), nor have I taken the tank off to see, but does that spare tank have the setup on it for a sending unit so I could hook up a gas level gauge? if so, I would like to get another generic sending unit (like on my front tank) and hook it up to a gauage in the truck. just poking around, you cannot see above the tank so no way to tell.