First of all, congratulations to General Hood for waking up his slumbering SEE!
911joeblow, I measured the hose, and that female is about 0.564" ID, with a 16 TPI thread, or close to it (hard to measure that small inside thread).
But it sure doesn't look like NPT by a long shot. And with an O-ring in the hose's connector it's highly unlikely that it's pipe thread.
I need to stock up on ether, so I can get a NAPA part number for those interested. They were in stock even at our dinky local store, and I don't recall them being overly expensive. Then again, I had more money back then.