From what I read on here. All that is correct other than some people have referenced a difference in the door latch area. Some say that there have to be changes made to put say, 51 doors on a 53 cab. Turn downs vs. push buttons. Whether that is just changing strikers or actually changing the metal on the cab where the striker mounts, has been unclear for me.
Actually won't matter for me I hope, as I will hopefully get doors and cab as a set.
What I meant by "up top" was more about having my existing 53 fenders and hood match up to maybe a 49 or 51 cab.
Larry W.