[dsraven]

if you look at a new aftermarket cab they say the cab fits all the task force years. I know there are some differences with the wiper motor mounting between the vacuum and electric and the bump in the cowl is different. I think the hinges have the same pattern on the firewall though, they just have different hinge spring set ups as the 58-9 springs attach to the inner fender instead of being connected on both ends to the actual hinge. if you look at the factory assembly manual it has the diagram of the cab and firewall with all the holes and dimensions of each mounting hole. that should show if there is a difference between the late years. I have that diagram printed off somewhere in my truck file because I replaced the firewall so I had to redrill the holes. I don't seem to recall a different spec location for the late years.
are you going to use a late cab with an earlier front clip? the frame on the 58-9 is also longer and the rad support mounts will be further forward, thats not a huge deal though. again, the assembly manual will show the correct location dimensions for those parts. it is a convoluted diagram to figure out, and it takes several dimensions to add or subtract before you come up with the actual dimension sometimes, but it is do-able with the will to continue