Dan - do a search on this forum for "Aristo cold light", or just "Aristo". You'll find a lot of info and opinion.
Keep in mind, thought, that the production of these lamps is tenuous, you'll find more by the same search in the forum for Product Availability. (however, these lamps can last a long time - my first one lasted 25 years)
I use a D2 with an Aristo head, new V54 lamp, and filter drawer for 6" filters and love it.