Years ago, I replaced the doors on my 88 coupe with doors from an 85 GT that I bought on Ebay. I did this, because the 85 doors had power windows, and because my original doors had very scratched windows in them. The 88 doors have an ajar switch right at the latch, so that unless the door is fully latched, you get an ajar light. The 85 doors did not have that, so I assume that 85 cars rely on the switch that turns on the dome lights when you open the door, to also turn on the ajar light. I transferred the 88 ajar switches and wiring to my new doors.
I don't know which models don't have the separate ajar switch, just that 88 cars do have it.