From the looks of the decals, rear inspection plate, handwheel, and motor style, I’d guess it is a Singer 66-16. Part of my daily entertainment is looking at listings and trying to figure out what model it is, regardless of what it says in the ad. I never know if I guess right or wrong, but I feel entertained anyway.
I’ve found several steam-powered sewing machines on YouTube, so I don’t know why one couldn’t be powered by propane. Although, a gas-fired generator large enough to produce 110VAC to run that particular machine might burn quite a little propane. It could re-define the term “sweat shop” if it was set up in a small sewing room in a home. After a short amount of sewing, one might want to slip off to an air-conditioned bowling alley for a while.
CD in Oklahoma