This...
[IMG]http://inlinethumb12.webshots.com/41931/2114747330096215731S200x200Q85.jpg[/IMG]is a correct 1951 door. And by a strange coincidence, it is on a 1951 truck! Like AD says, this truck was also available with the deluxe(5-window)cab, but the farmer who first worked this particular old girl had no interest in fancy-smancy gewgaws.
If this door had a pushbutton handle it would be correct for '52 & up, and if it had no vent(no-draft)window, '50 & back. Mind, though, that all these doors were interchangeable from 47/2 to 55/1.
As to the engine, the quickest way to tell a 216 from a '55 235 is the valve cover. This..
[IMG]http://inlinethumb44.webshots.com/44075/2412351800096215731S200x200Q85.jpg[/IMG]is a '53 216. a '55 235 would have 4 bolts holding the valve cover to the head; 2 on each side.
(Left-click on either image for a bigger version.)
