Jerry,
I only know from my 4400 frame off, but the cab has to move backwards as well as upwards to clear the steering column (if left in place). The others can confirm, but I doubt you will be able to clear the front of the bed. The steering column is not that hard to remove and it will make removing the cab more feasible. Just do it. Might as well remove the bed, too, if you're going to all this trouble. Just sayin' ...
You get to the rear cab mounts from both inside the cab and from underneath. It's fairly straightforward -- especially if you have a helper. But the seat frame/tray will hold a wrench in place while you work from underneath (voice of experience) with a ratchet if you don't have a helper.
Good luck!
John
