Head Bolt/Temp Sensor?? 59 Engine

[expavr]

The attached photos show a head bolt/temp sensor in a 59 engine that came from a 46 military COE fire truck. There is a temp sensor on the left head in the usual location, but none on the right head. Also the use of head bolts instead of studs? Would this have been common to this application?

 

[Barlea]

Not a temp sensor, but a headbolt block heater, 120 volt, plug it in so the engine will start on very cold mornings. Looks like it's missing the electrical "male end" top that the electrical cord connected to. ..B.

 

[expavr]

Not a temp sensor, but a headbolt block heater, 120 volt, plug it in so the engine will start on very cold mornings. Looks like it's missing the electrical "male end" top that the electrical cord connected to. ..B.

Thanks. That makes sense considering the truck's emergency application and location in the NW.