Join Harry Taylor's Omega enlarger forum at www.classic-enlargers.com, and all questions will be answered. I believe you can put a Super Chromega II D head on a D-2 if you change the lifter arms, which are a bit different on the later enlargers than on the D-II and D-2.

If you have the variable condensor head (D-2V), then there is only one set of condensors. You change the position of the lens in the middle, I believe, for different focal lengths.