When ordering parts sometime you have to look up MF50. Parts are the same and also MH 50. Like Tony said the 35 is same as far as engine. Most times they don't show F40. I have 5--F40 and don't have any problem getting parts. Parts like tail pipe and bottom radiator hose you have to ask for early MF50 gas.They are very good tractors. The only difference is the grill on 56-57.