I own a 69 Mach 1 which the PO had a 351C with a FMX. This spring I have to choose between rebuilding or replacing the tranny. I do not race it, but drive it every day. Fuel economy is the least of my concerns. Would there be any good reason to replace it, it's served me well for 6 years. Enlighten me with your knowledge and let me have your opinions.
