The early & late OVP's have totally different pinouts. They are NOT interchangeable, period. I believe the early style was used through model year 1987 in the USA, and the late style was used starting with model year 1988, but I'm not sure if that applies to all models of W124.
Early, p/n 201-540-08-45:
Late, p/n 201-540-37-45:
