I have a 1974 corvette "T" Top that has a black toggle switch on the drivers side {just beside the throttle, gas peddle}.  It appears to be a factory installed switch. There is also a wire inside the battery compartment that is not attached to the battery but has a treminal connector on it.  I thought it would be wise to check with you all before I do a 'smoke test'  Any thoughts or ideas are appreciated.  Thank you , Steve

Gonna have post a pic.  I don't think it is a factory switch.  Maybe for an aftermarket power antenna?

Should be a pull down switch to pop up the headlights. 

Rear window defogger switch?

Agree that a photo would help. If it is built into the right side kick panel of the driver's side footwell and looks like a small version of a household electric paddle switch and is the same color as the kick panel it is most likely the rear defroster switch. Unless it's disconnected or the switch or blower motor is burned out, you should hear the fan kick on just behind the drivers door on the "C pillar" when you switch it. Unfortunately I don't have an explanation for the spare wire in the battery compartment.

Good luck!

Next question is do you have a rear window defroster?

It is for the rear window defogger. Silly place to put it, but that's where it is...

They used two different types of switches, early, and late.