The Ram has an onboard 33 gallon tank. While this is my first diesel, I do know that these things, under no circumstance, should be allowed to run out of fuel. It’s not like gas, you actually have to bleed the fuel line or rail or whatever, in short no fun, don’t do. So I added a 60 gallon transfer tank and wired the transfer valve into the auxiliary power system so all I have to do is push a button on the center console and it starts draining fuel from the 60 gallon tank in the bed into the onboard tank. Effectively tripling the range so we’re expecting at least 800 miles while hauling the RV and somewhere in the 1800 mile range not towing.