I think the Carter and the Chevrolet copy, marked "C", of the Carter were the only original carbs for the 37 Chevrolet cars and trucks. I don't think Rochester Products were the ones making the Chevrolet copy, but I don't know when they were bought by General Motors and started producing carburetors. The Carter is simple and generally trouble free, while the first Rochesters tended toward warped bases. Maybe carbking will enlighten us.