I believe how the probe works is there is a magnet inside that jumps every time a metal object passes by it, so as long as there is some metal bump for the probe to react to it should work.

I mounted my probe on a bracket bolted to the side of my transmission and stuck a rare earth magnet on my axle. Twice in five years I've lost the magnet (that's five years of daily driving, rallyX driving, highway driving - probably 200,000km). The hard part is getting the probe close enough to the target object for it to pick up a signal (it need to be real close).

Also, the two wires coming from the probe need to be connected the right way round. If you spend three hours crawling under your car trying to get it to work to no avail try switching the wires around.