Resistor Wheels

[twilight]

Any one have a reliable source for resistors to make resistor wheels for block detection? My club is soon going to require that all rolling stock should have them but I need to do a couple of cabin cars right now. I know the value should be 10K for single axle application, but not sure of other specs, tolerance, or power rating. Please fill in the blanks if the later 2 specs are important.


Thanks,

Mark