I have just purchased what I believe is a pre 1955 civilian 302 GMC engine. (At least that is what I think it is). I do not have it home yet to get numbers off it, but this I know, it does not have side motor mounts and it does have the right side front of engine mechanical fuel pump. I am sure that the engine was set up to run on 12 volts, at one time, as it has a late model GM 6 cylinder HEI unit installed, but I do not have the starter, water pump, carb. and alternator. My question, Will any 6 volt GMC starter, 228, 248, 270 and 302 interchange. I suppose I will stay with 12 volt and run it against a 6 volt starter (if I have the 6 volt flywheel). I am not sure what flywheel I have yet, but hope to know shortly. Any help is appreciated.