Usually the only diffrence in the the sensor is the connector. Bosch makes universal heated o2s with 3 or 4 wires. I'm pretty sure yours has 3. When replacing it, make sure the wires are soldered and shrink-wrapped. The final step I suggest is to moniter the o2 signal with a lab scope and go for a drive to make sure it is switching in which case the o2 is working. The o2 costs around 75$ cdn and should work.
'87 300E 325,000 km