I bought my first Aristo head in 1981 for a D2, and I seem to remember that it was the same head for the Beseler 45 series, with an additional adapter, which I think was a ring of some kind. Someone else will know for sure.
I did a quick Google search of "aristo cold light with beseler adapter" and found this - an old APUG post:
Search the forum and you'll probably find something.