all the holes on teh vauxhall engines are Metric 14. M14x1.5. the above is a GM pressure sender used on nova and astra gte's. you can use the same position with an adapater. just above the pressure sender in the picture is the turbo oil feed, as the picture is a 2.016v turbo engine. on non turbo engines that has a blanking plug in it, and ideal for more senders. again its M14x1.5 thread.