Nope, that sensor is the one for the gauge on the dash. The one posted with the 4 pins is the engine computer temp sensor. It is available, its also known as the Water Temp Sensor on Fastlane:

http://catalog.peachparts.com/ShopByVehicle.epc?q=&yearid=1989%40%401989&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6201%3AMBC|1507%3AED|10000013%40%40300E&keyword=sensor&subcatid=P:240675@@Water+Temp.+Sensor&mode=PA

A pic:

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)