1972 Cheyenne Super with 1971 parts?

[Pick8208]

Hey everyone, I'm new here and have a question:

I recently bought an orange and white 1972 Cheyenne Super 1/2-ton 4x4 from a friend, and I'm trying to figure out exactly what year it really is. The title lists the truck as a 1972, and the VIN supports that, but it has 1971 door panels, no phillips head screws on the upper inside of the doors, a rear-view mirror attached to the roof (rather than glued to the windshield), and a throttle arm rather than a cable going to the carburetor. I know that GM sometimes did running model year changes, but this seems a little far fetched... Could this thing really be a 1972 without all the 1972 changes?