i recently purchased a 52 chevy 1/2 ton chassis that came with a 270 gmc jimmy engine with a 3 on the tree tranny. can anyone tell me the difference between the 235 engine and the 270 gmc? the 270 came with an alternator does this mean it is converted to 12 volt. should i keep the 270 or replace it with a 1950 235 with a 4 speed that came off of my 3/4 ton chevy. do you know if fenton headers fit? please help me