Front indicators are earthed through the screws that hold the housing into the bodywork, so if you have two wires, they will be US spec twin filament. You can still use these as per normal UK spec, you just need to wire up the brighter filament of a twin filament bulb to the indicator, and leave the sidelight one disconnected (move the wire to the headlight sidelight bulb).
Sent from my iPad using Tapatalk