1972 k10 doors

[MikeandCheryl]

i have 4 of these. 2 are green and contain all the guts that came with the truck. Windows work, door panels are there, mirrors are there. All good. I also have two spares. Shells only, and with speaker cutouts needing some TLC. I've read that 1972 doors are different than previous 69-71 doors. i'd like to know why and what. My old doors might be originals, and worthy, and the spares that were included in the sale might be something different. Anybody out there can tell the difference between the two? Do tell. Pics are good tonic. Thanks all.