Well ****, 55gal drums never even crossed my mind, and there's surplus drums everywhere around here for dirt cheap too. Though, rather randomly, I did come across an 80 gallon fuel tank not too long ago on CL for $100 that I ended up grabbing, really as more of a replacement the pickup saddle tank that a PO added to my '59 International 2 ton truck...poorly. Looks like he just lopped off a section of frame rail for the hanger mounts from the pickup, used copious amounts of gorilla snot and bubble gum to "weld" that frame chunk to the frame of the International under the flatbed, then hung the tank with factory straps. Not to mention, that tank looks completely out of place on a truck like that. The 80 gallon one is basically a long rectangle, 17" high/deep, 64" wide. No idea if it was a factory tank out of some equipment, or an aftermarket, or intended as a transfer tank, but it definitely looks much more "correct" hanging under that truck. Does have what appears to be a factory welded filler tube on one end, as well as a NPT threaded port centered on the top and bottom. I haven't yet pulled them out to see if it's set up as top vent/bottom feed, or if it has a pickup tube on the top with bottom drain/vented through filler cap.
As that truck isn't going to be on the road for a bit still, I may end up strapping that one down to the trailer for a while or doing a quick frame for it to rest on in the back of the Chevy pickup as a transfer tank so that the fuel outlet on the bottom will clear the bed. Either way, I'm planning on contacting AZDOT before doing any of the above to verify what is and isn't legal here. More so if it ends up underneath the International, as anything 1 ton and larger is automatically registered/plated with commercial plates in Arizona, regardless of whether it's used commercially or strictly personal. Thankfully we're not required to carry commercial insurance or deal with DOT logs and other commercial regulations like that if it's a personal vehicle, and I doubt any LEO is going to suspect an antique truck of running commercially, but I can't find anything that deals specifically with personal use of "commercial" vehicles like this. This has been the source of much confusion for many of us, as there really isn't a clear delimiter of what applies when using large trucks for personal use that isn't RV related. Which is understandable...not many people want to use medium and heavy duty trucks for personal use when modern light duty pickups are plenty stout enough.
