Years ago there were light fixtures in houses like you describe. They were not grounded receptacles, nor did they have GFI in them. Trying to find them today would be a tough job. You probably have one that was wired for some 110 as well as 12V. My old Coachmen has 110 receptacles, but all the lights are 12 volt. It is a 79
If you are determined to find and use them you could put a GFI in the main 110 connection. Look at old flea markets and junk stores, possibly habitat for Humanity Restores.
I worked at a place that had a trailer at one of the out of the way plants. If you didn't jump in or out of that trailer you got a jolt.