These 1986 models were supposed to be no option cars, meaning you could not change the option list. But I have noticed at least 2 differences in vintages of these cars.
The first was paint around the 1/4 windows. Some had it, some didn't. Example pics below.
The second thing was the rounding of the roofline where the new window meets. It has been documented that the factory in michigan just used a hammer and pounnded the roof in, and then smoothed the corner with bondo. Most rough condition 2+2s have the bondo cracking on them. Some had a sharp corner, some had a smooth corner. Here is an example below.