Kanedog,
There are no magnets, the hall effect pickup sees the holes in the rotor / disk on the QD models and a bolted on 9 tooth spline on the chain case models (Same setup since Polaris went to digital instrumentation). You can either mount the 9 Tooth spline to your drive shaft (mounts to the end of the drive shaft, below the driven clutch) or locate it to pick up the holes in the CMX rotor.
To convert the sensed pulses from the stock pickup to the quantity the MFD is wanting to see, to be accurate, you'll want / need a SpeedoHealer from HealTech Electronics. I am a dealer for them and so is Blue Monkey Motorsports in Idaho. For more specifics you can read my thread about fixing your Speedo;
http://www.snowest.com/forum/showthread.php?t=377709
It is a small / lite Plug and Play unit and will get you what you are wanting to achieve for very little cash outlay.
