I have a 1988 W124 (300E) and suspect my OVP Relay is bad. When I search for a replacement only 9 pin versions part number 2015403745 come up. The relay that is currently in the car is a 7 pin with part number 2015403245. I can only find those listed for sale used and would prefer to put a new part in. Can this part still be found or are these two parts interchangeable?