New Standard T-Series vehicle speed sensor.  Also known as a VSS.  This mounts on the transmission tailshaft extension.  This is for automatic (4L60E) transmissions only, and mounts on the RH (Passenger's) side of the tailshaft (AKA OBD2 models).  Fits the following:

96-02 Camaro (all models) w/ automatic transmission
96-02 Firebird/Trans Am (all models) w/ automatic transmission

NOTE : OBD1 and OBD2 4L60E's use different sensors!  OBD2 sensors are on RH side of tailshaft, OBD1 sensors are on LH side of taillshaft.