The VR V8 only has one sensor, its on the left of the engine (as you're looking under the bonnet it will be on your right side) just past the point where the extractors form into a 'Y' shape. You can reach it by jacking the car up and turning the wheel to lock in the right direction. Not sure what you mean by shifter, it should unscrew easily if anti-seize was put on it. Make sure you get a genuine AC Delco one unless you like soldering wires, because they most likely wont be long enough to reach the pigtail connector on the loom in your engine bay.