Any 3/16 ball bearing cone
While it will work, spacers may be needed and not all have the shield plate/dust cover in them.
It may be cheaper in the long run to find a reduced one on CRC/On-One or similar in the bargains pile and match the axle cones up with the models. You'll get bearings as well.
This site is good for finding compatible cones, SJS* if you find the cone is also quite good
http://www.moruyabicycles.com.au/conten ... front.html
so you'll find any of these have the 'correct' replacement cone
Suits HB-M525 (Deore - Disc), HB-M510 (Deore), HB-MC33 (STX-RC), HB-MC32 (STX), HB-MC30 (STX).
Wheels Manufacturing also make replacement (though expensive) cones
http://wheelsmfg.com/shimano-front-hub- ... cone-chart
http://www.sjscycles.co.uk/shimano-hub- ... pt422_pg1/
*there is another shop out of the many that is often cheaper then the rest, I cannot find my link though.