when did GMC switch to (-) ground? Was it when the whole company went to 12v? V8 equipped GMC (I don't know about the really big trucks) trucks switched to 12 volt positive ground with the second series 1955 models. Six cylinder equipped 10x through 41x models which didn't change until the 1956 models.
'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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