Originally Posted by div4gold
If I added another fuel tank in a CJ3B under the passenger seat what's involved? Mainly trying to figure out how the filler plate is attached to the body.
The filler neck panel is just spot welded to the tub and with only the rubber grommet on the tank neck. You will need to get the tank neck "reversed" to use a stock tank on the right side. Unless it is an aftermarket body without the tool box, all the tool box panels will also need removed.
Some reason you don't want to go with a rear tank? To me, the tool box storage space is highly desirable and I built my own since my 3B glass tub didn't have one and because I wanted a solid mounted passenger seat. If you have spent any time in a flattly, you know storage space is extremely limited.
Also, you can get a lot bigger tank in the rear.
Here is a good thread on installing a rear tank.
Gas Tank - Installing Rear | SSDutch CJ6 Jeep Blog | Boyink!
I built my own rear tank and managed to get 25 gallons by outboarding the rear cross member, moving the middle tub mounts over the frame rails, and using the extra space created with a 1" body lift. At 25 gallons, there really isn't a need for two tanks and I haven't used a Jerry can since the install either.