"The ballast resistor is on the firewall in the engine compartment (driver's side) on a 55.2, but I am not sure if this is also true on a 55.1. It's usually a whitish/ cream color."1955.1 would have been 6v, originally.
Nonetheless, I have always seen/put a 12v-system ballast resistor on the upper firewall of an A-D truck that has been converted to 12v (as Brad posted was done on Task Force trucks). Is there an additional insulator/standoff for the attachment bolt?
But,
here is a ballast resistor mounted on the coil-bracket .
https://www.chevsofthe40s.com/detail/19577/Coil_Chrome_Bracket_Only.html 
