The front headlights, however, were designed for Power Function lights (which incidentally are a much more flexible system than the old 9V train lights), which are not compatible with the 9V engine. Therefore, my HE still has an IR receiver and battery box and you need to use the remote if you want to turn the headlights on.
All you have to do is buy the adapter cord for 9v -> power functions. I can’t remember if you have to modify the power truck or not but mine has a cord that runs from the motor into the locomotive, into the adapter cord and to the lights.