Is this my orig starter switch? There's some confusion about this one...

 

It certainly looks like an original.

What's confusing?

 

Some stuff the PO had done since 1951

 

Does it have one or two terminals? '51 and back should be 1 terminal, 52 and up should be two terminals. I think I see 2 terminals there?

 

OK, so if it has one terminal, and your truck is a '51 and still 6 volt negative ground, it works by providing frame ground to the starter relay. The contacts on the sides of the switch that hold it into the dash also provide that ground to the contact when the switch is depressed.

 

Yeah after poking around it's a 51 6V switch that just grounds the circuit. I'm gonna get a two-contact momentary switch and put in there for our 12v system.

 

NAPA sells them, NAPA AUTO PARTS - Starter Switch