I'm swapping a Cummins into my gas-powered Class A motorhome. Can I use the 50-gallon gas tank for diesel?

 

Yes there is no reason why if it has a intank pump you may have to change it

 

The motorhome has no in-tank pump, the fuel pump is all mechanical. But wouldn't a low pressure inline/in-tank pump be helpful to the Cummins?

 

You will want to drop the tank and remove the strainer sock from the end of the feed tube. I had a problem with that and could not figure why fuel would not feed, I guess that strainer is too fine to flow diesel well.