Suburban furnace supply line nut size?

Not enough room to trouble shoot suburban furnace, I have to pull it out and work on it in my carport. I need to know what size the female supply line is so I can hook up propane to it. So I don't have to
Drag the thing to the store with me. Electric wires just going to extend, 15 feet.

Model is sf-30

Anybody know the size?

Thanks