Not very precise ...
Door Handles
by Karl von Salzen
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68 are one-year-only: they used pushbutton handles [ala 67] and the lock knob is on top of the sill.
69-70 are the same, lever action door handles and lock knob is now a lever above the inner handle.
68-70 are L code keys.
71 and started the vent system thru the door: slots in the leading edge and the slider in the rear. 71 and up are R code keys.
68 to mid 76 hinges are the opposite of mid 76 to 79 hinges.
Around 75, the lock knob moved back to the top sill like the 68 door. But the 68 door does not have the front air slots
I guess it must be 1968 model year only?