As for the codification, if I remember well, you first start with the model, then you have the material of the case, then the material of the strap or bracelet, and you end with the dial color OR random number.
The MUT models were steel, white gold, platinum, skeleton, rose gold, and steel jeweled ( jewels on the bezel only ).
Production figures are not communicated.
The white gold grey dial was featured in the 2004 / 2005 catalog, not after, not before, AFAIK.
There was another white gold version with the silver dial, circa 2002, though.
Best,
Nicolas