I called Hunter for my 410 and..
they sent me to Selden (my mast is a Selden) saying that they put the light on the mast. Selden was great and told me the make and model and part number of the light and the specs and part number of the bulb. Boat US had the bulb. Now all I have to do is to convince the admiral to help me go up the mast with my ATN climber and change the dang bulb.