Well fella's, my experiance is that gear boxes, either jet engine accessory gear boxes or a car's diff/tranny make most use of magnetic plugs. Because there are obviously bearings and gears messhing together and alot of moving parts. It would benefit engines's too but mainly I have allways seen these type of plugs on gear boxes. I owned a Nissan XE 4x4 and it's axle diff's had magnetic plugs and so did the transmission. But not the enigne. Not sure why, but engineer decided on that.
Hopefully someone will come out with an exact fitting plug.