I want to put a small auxiliary tank in my box to extend my range when towing. A friend has one for sale, but it's a diesel tank. Can I use it for gas? Any major safety concerns? It's an actual aluminum tank, with a fill system that connects to the factory fuel fill hose. Can I use this on my gas truck?

 

I have friend that put a cummins in a gas f350 and used the original tanks over, I dont see what the issue would be as long as you get it cleaned out pretty good

 

Be prepared to get some fines from the DOT. Hooking it up to the fuel fill hose is not DOT legal as far as I know, and I'll bet that tank isn't approved for gasoline. Diesel and gasoline are in two different categories. Gas being considered explosive, where diesel is not. Do some checking around in that dept before you do it. Otherwise, mechanically, you shouldn't have any issues. Same as the diesel guys.