Did you just buy the one on ebay? Somebody has.
If you did then please make sure you get the Siemens part with the cable. I mention this because in the description the item is described as:
"A Brand New Genuine VDO Siemens Camshaft Sensor with wiring harness
In a fuel parts box (CS1292G)
Vauxhall Part Number 93171450"
& also
"Brand Intermotor
Manufacturer Part Number 18960
Type Camshaft Sensor
Notes Colour: Housing Colour: Black, No of Poles: 3, Part Detail: Inductive Sensor, Without Cable, ...."
AIUI you car will have square sides on the connector, unless the sensor has previously been replaced. This being the case you need the cable to modify your harness to the later type. If your car is already nodded then you don't need the cable.
The part that dave the builder linked to might also be the Siemens part with adapter cable. 'Might be' because the additional "N" in the GM number usually means not genuine GM but an aftermarket. You want a genuine Siemens. 93171450 appears to be the Vaux part number for the sensor with an adapter cable.