I recently converted an F3-B from DC to DCC. The decoder used is the same one for A units as well as B units. Since B units don't have headlights, they assume you will either cut or unsolder the LED from the board. I did not. I left it on initially for testing sake but then I had an idea... why not just bend it over backwards and leave it hooked up to look like someone left a light on inside the B unit or was still inside working on it? Since I already had the camera set up and had the right light levels, I also took another couple of night shots just for the Hallibut.