Rear gas tank installation help????

[Hazieview]

I have an '87 shortwheel base fleetside chevy with drop shackles/hangers and spindles. I was wanting to put a gas tank in the rear and eliminate the two side tanks. I tried to use an old suburban gas tank but it was way to big. Any suggestions on what tank I could use? It just needs to be a little smaller than a suburban tank!


thanks for your help!!!