Hello all...I have a 6 volt '55 ford V8 Y-Block that came without the stock dual temperature sending unit setup. An aftermarket sending unit is in it's place on the driver's side head and the guage hangs under the dash. I want to make the original temperature guage in the dash functional again.

This past winter, I bought the two sending units the specs call for; a single-pole and double-pole. I read that the single-pole unit goes in the passenger side head and the double-polled unit goes in the drivers side head. I also bought the wire that connects the two. I expect the wire that is dangling from the wiring harness is the lead that goes to the guage in the dash...

...but...I get the car out of storage and go to install these parts and find a freeze plug in the passenger side head where the single-pole temp sending unit is supposed to go. Now I am confused. Anybody out there know what might be going on?