I can't figure out how to wire the thermostat, transformer, fan/limit switch, and an electrical cut off (to pilot light) in my 1945 Armstrong Furnace. Help!

You may wish to talk to an electrical contractor, if you need to be up to code. Where I live, it would not be legal for the layman to do this kind of work. Your laws may vary, but it’s worth checking them out.

I was going to say essentially the same thing as @laureth . The building codes are usually very strict about that type of installation, and if you don’t know exactly what you are doing, you really need the guidance of an expert professional.

Okay, I’ll be right there. Have a beer ready.

Wiring a thermostat is one thing, and though I’m not familiar with electrical codes at all I can’t imagine that any US building codes prevent users from installing their own—or I don’t think that they’d be so readily available and popular at Home Depot and Lowes, et al.

But an electrical cutoff to the pilot light on a 1940s vintage furnace sounds like something else. A gas furnace of that age is not going to have electronic ignition, but a continuous pilot light that’s not intended to be turned on and off (not that I can see a reason why not). I don’t think an oil furnace would have a pilot light—but I could be wrong about that, too.

With all that you’re trying to do, I guess I’d want a competent, qualified—licensed—electrician, too.