When it comes to the 67 window regulator handles on my interior decor equipped car, I see that the 67 MPC calls for C5ZZ-6523342-C regardless of interior type. The 60-68 MPC has this used for 65 (from 3/8/65) through 67.
But the handles on my car are stamped with C7ZB-6523348-A.
I get the engineering vs. part number discussion, but what confuses me a bit is the C7 stamping. To me that means that there were engineering changes for 67, but perhaps not enough to cause a change in service parts, which would make the changes cosmetic or perhaps something that does not affect fit and function.
So if I happened to find NOS C5 parts in a box, it could be a Forrest Gump situation - you never know what you are going to get (like chocolate). Could be a C5 stamped part, or a C7 stamped part, or C6 if there was a variation for that model year. I'm I thinking this through properly?