Diesel Transfer tank under truck flatbed?

I have seen a few people mount a diesel transfer tank (100 gallon rectangle or small 50 gallon square tank with fill-rite pump and hose) under the truck flatbed where one usually mounts a tool box. Is this actually legal? Transfer tanks are typically mounted in or on the truck bed, not under.

If it’s rated to be a saddle tank it doesn’t matter whether the fuel in it goes to the truck it’s on or to a machine. I’ve never heard it wasn’t an acceptable way to transport fuel. Other than an direct impact it’s probably safer than a lot of aux tanks out there.

Mount it securely & move out with it !

I just went through this with a truck I am putting together, and like junkyard said, if it wasn't made as a saddle tank to go on the side of the truck, as far as I have been told, it won't be legal, that's here in Connecticut anyway. I can't answer for anywhere else. You can always set one up and try it but, if the truck police pull you over you may have an issue....

I have an 50gal dump truck tank under the flatbed I had to plate the top to support the pump and weld in the threaded bung
I would have no problem at all running a custom built tank securely under the bed nowhere does it say where you can mount a transfer tank and the dot would have a hard time saying otherwise

Auction purchase of new twin 40 gal propane tanks with the factory mounts just happen to fit nicely between the cab and front flaps on my F-550. 1" transfer line across the bottom and 1/2" vent line between them at the top keeps filling and pumping simple.

This subject came up a while ago with the manager of our local petroleum plant. He said a dump trucker had a real slick setup like this on his dump truck with a dispenser for his machines but they had to ask him to stop because if the gov't reviewed the security videos it would look like they were allowing him to put red diesel in his truck and they are concerned they can be held responsible for this.

Not saying it is right or wrong, but just what happened around here.

I have tanks mounted on both my transport trucks now both tanks are under 50 gallons I just dont need to carry more on a truck been stopped by dot on both trucks the one never said a word and on the other that poor cop spent 15 minutes trying to figure out if it was plumbed to the truck and after he determined it wasn't then questioned if we were using our 50 gallon red fuel tank to keep our 300 gallon truck tank topped off

Needless to say the old man and the dot sergeant had a pretty good laugh over it