The black and yellow is an '87.
The fades generally followed, and I'd guess it as an '88.
The decal/font styles can sometimes help you out. '88 was the squiggle year, the '87's were more mundane.

I've not seen a lot of difference in the later Lemans vs. Lemans RS. The RS sometimes had better wheels, but I've seen purple fade Lemans and purple fade Lemans RS's that looked identical.