No the 600 series at least the 641 came in gas or diesel. mine is a 1961 641 D-10 it is diesel. one thing I am wondering though is it came with a backhoe on it and does not seem to have the connection to connect a 3 point hitch, does anyone know about that? was it an option or something? how can I add that functionality?Have you tried Steiners yet? If I remember correctly. The 600 series is gas. Diesel is a 800 series. Or at least that is what it says in my Ford Service Manual.
Ford 800 SERIES