[rotorwrench]

The F2 will have a "D" in the number prefix and the F3 will have a "Y" in the prefix where the F1 has the "C". The F2 & F3 have the longer beds to correspond with the longer frame and both have the Timken/Detroit rear axle with the 8 lug hubs. The top shift 4-speed T8 or T9 transmission was used.

It's not uncommon to have a cab change on these old trucks. They like to rust and it's a common way to fix a real rusty one since all the conventional cabs are the same between the three types.