Da Vinci Tourbillon Ref. 3752

I am very fascinated of the Da Vinci Perpetual Calendar (Ref. 3750) and its variants like the Rattrapante (3751) and the Tourbillon (3752). And since I now like to add a Tourbillon to my small collection of the classic Da Vinics I did some research on it in the old catalogues and pricelists as well as online. Common knowledge is that the following numbers have been produced:
Reference 3572 (9267 with corresponding bracelet):
Yellow gold: 200 pieces
Platin: 50 pieces
Four Seasons: 20 pieces
Leonardo Da Vinci: 50 pieces

Now I found out that on an auction in Geneva 11/2010 a version in white gold was sold that was of a limited run of 50 pieces. The case number 288XXXX suggests that it was produced 2002/2003. Is there any more information about this model available? I couldn't find anything yet.

And have there been any other variations of the 3752 Tourbillon?

Have a nice weekend!
Matthias

Here is an update on my own post.
Thanks to the always generous hospitaity and help of the people in the IWC Boutique in Munich I now know the following.
According to the information of the IWC Workbook there have been 6 versions of the Da Vinci Tourbillon:
375201 - 04: Yellow Gold, 200 pieces
375205 - 08: 4 Seasons in Yellow Gold, 20 pieces
375209 - 12: Platinum, 50 pieces
375213 - 16: Leonardo Da Vinci, Yellow Gold, 50 pieces
375217 - 20: Leonardo Da Vinci, Red Gold, 50 pieces
375221 - 24: Leonardo Da Vinci, White Gold, 50 pieces
Each reference group consists of the 4 language versions German, Italian, English and French  

But still my questions remains unanswered. Were there really 50 pieces of each Version of the Leonardo Da Vinci (a total of 150) built and sold? Has anybody ever seen the Red Gold version? 

Have a nice day