The other day I was telling a fellow co-worker about the Single Carb Conversion I was doing. (He looked at me as if I was an idiot)He told me that the Original 4s were the best option. (HIS OPINION) I told him that the slides for my carb were hard to obtain. He stated that the 75-79 slides were all the same! I told him not so, due to the EPA forcing the bike companies to lean out the carbs for emissions reasons.(IMO) I dont recall if they are interchangeable, But if one does that, isnt it impossible to get the carbs to run correctly??:?