I have a D2 with a variable condenser light source and a 4.5 inch condenser. I bought an Aristo Cold Light Head today. It looks new in the original box. It s ays it is a D2, W45. It is two parts, a top section with the light and an end c ap with a cream plastic part. It looks like a hat. I have removed the light ho use and can not figure out how to install the cold light. There are no brackets on it. It looks as though it sets somewhere in side the original light house. All so what takes the place of the condenser housing to hold the negative in pl ace? I don't believe I have the wrong cold light. It is clearly marked D2. An y one with directions on how to install?