Try : http://www.khbphotografix.com/
Maybe 3 or 4 years ago I went there to purchase a variable condenser head for my D2. They were most helpful.
You can contact them at:
335 Admiral Blvd, Unit 13 and 14
Mississauga, Ontario, Canada L5T 2N2
Fax: (905) 670-3293
I hope that this will be useful to you.