IWC and the late Afghan King Mohammad Zahir Shah

Is it possible to know how many IWC's (Cal 89) were sold to Afghanistan until 1973?
In 18/4/02 forum member Glen Browley posted a picture of a IWC Cal 89 with the signature of the Afghan King Muhammad Zair Shah in the case back in ornate arabic caligraphy. I've recently been to Kabul and, after much searching, found one such IWC in relatively good condition. It is now a treasured addition to my small IWC collection. I was told these are rare items because the king did not give away that many and those who got them treasured them. How rare are they really?

congratulations;but I doubt there's more info (nt)

Thanks Michael. I had low expectations...

I just hoped one of the IWC gurus could dig up obscure and forgotten data. Numbers/rarity are not important, in this case. What trully matters is that it is a beautiful watch with a story. This one is a keeper.

It is a C.8541B NOT a C.89