Hello, gents. longtime reader and visitor to this great site. I just picked up a complete heater for these ol' trucks name tag say's Harrison i believe. it has an round aluminum plate with chevrolet on it. anyhow i want to check if the motor turns. without burning somthing up, can i connect the two wires (neg and Pos.) at the motors end to a 12 volt battery direct or should i use a reducer to bring it down to 6 volts.

the heater looks to be in excellent shape and i intend to put in my 51. thanks.