Well, yes, the decimal point does matter, but like Lightholder's Dad pointed out, they have the correct one, as would many other suppliers. Thanks for getting that straightened out.
If you have the choice, the 5 watt will be better regarding the heat generated. It will be physically larger, will it fit? It's hard to say what the current through the resistor would be, that and the voltage drop multiplied would give you the minimum wattage needed to make the resistor survive.
Does the gen with the tach output have a special shaft too?
