Ken, I don't think you need to open up the switch in the bay to tell its voltage rating. You should be able to just expose the wiring by peeling back the corrugated sleeve (aka convoluted split loom tubing) running into it, as per your photo; that's of course common for protecting and making-neat 12v. automotive harnesses, and has a slit along it to facilitate slipping over wire bundles. I have rolls of various sizes over my workbench. There's likely just a power wire in and one out of the switch, and maybe a ground in and out.
Then like Steve notes, if it's a factory installation you may be able to read what's stamped on the wires inside that split tubing; there won't be enough wire in the switch to read any printing along it anyway. That said, others here with more historical perspective would have to speak to when wire printing started, as your year may have been prior to. I'd also try to follow that loom tubing as far as possible to see where it goes, although, as is common, other wires may join it confusing the traceability.
It wouldn't seem plausible for the factory to install AC wire exposed in a bay like that, loom tubing or not, but who knows what previous owners or techs may have done.
My initial guess on the overhead switch would be the Aladdin Reset, as that area is a common location for it.
Joel
