I know a 5 speed manual is a ZF5... I have a 2000 F-450, that has 6 speed. 1-5, reverse, and a "low" gear. Isnt there a ZF6, and if so is that what I have? If that isnt what I have, then what do I have? Thanks for any help.... and if you happen to have such a critter for sale, please do...