Chevrolet (and GMC with a positive ground) small trucks used 6 volt electrics until second series 1955. GM started their change from 6 volt to 12 volt cars with Cadillac, Buick and Olds in 1953. Pontiac and Chevy cars changed to 12 volt in 1955.
The 6 volt systems did not use any resistors in the ignition system, internal or external to the coil.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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