We have used a long thin tank from dual tank pickups and mounted between the frame and driveshaft with a side fill (tan 46) or a 13g one from a Blazer (Bronze 40). The 21g Blazer tank hangs down too much if truck is lowered at all. Sorry no pics on the 40 installation but it is very near the same as the one on a 52 (pictured but with a 21g tank). It has the side fill tube with a motorcycle flush fit cap in the fender.

[img]https://s9.postimg.cc/eqmrq13e3/Trigger_005.jpg[/img]
[img]https://s9.postimg.cc/t9twrhtyz/Stude_Justin_s_40_Cougar_Cat_004.jpg[/img]
[img]https://s9.postimg.cc/q49b0xvtn/003.jpg[/img]
[img]https://s9.postimg.cc/dcv4ujgxn/004.jpg[/img][img]https://s9.postimg.cc/
[url=h...://s9.postimg.cc/8e7mg17zv/008.jpg[/img]

Evan