Some of the 96 motors were a transition model where they used M42 parts on the M44 engine. One of the changes from M42 to M44 was that there were two separate coolant sensors on the M42 and they were merged into 1 on the M44. IIRC, one went to the cluster and the other to the DME. Both are right under the intake manifold. Pretty sure the M44 version is 4 pin.
Here's the early (M42) diagram showing the sensors,
http://realoem.com/bmw/showparts.do?...05&hg=11&fg=15