I bought a unit off ebay. It has a replaceable bulb. The mounting points are correct. You have to adapt the wiring a bit.
It came from K&L Supply Co. 1040 Richard Ave. Santa Clara, CA 95050 P/N 23-8104 The bulb that was in the kit from K&L was a 25w unit. The place where I bought it from had changed it to the proper 6V 15/15 item.