I'd expect that the extra wires would be for different rotation, requiring some internal rearranging same as on an AC motor .... the single speed would be normal for a heater fan, with the dash switch supplying the resistance necessary to provide the reduced speeds of lo and med
providing you think it's turning the right direction for your fan blade, should be fine hooked up like factory, red wire to the switch, black to ground, inline fuse from switch to a power source
Bill
