Dear elam,
even if the SS Senator Perpetual with a grey dial is not listed on the GO web site it seems to be available in reality. I assume it has been discontinued, but it seems there are samples remaining on the market.
The new cal 100 based Senator Perpetual SS grey has the number 100-02-04-02-04.
There are even single samples of the former cal. 39 version around. Its number is 39-50-14-22-04.
The cal. 39 models were superseeded by the cal. 100 line in 2005. Art wrote an article about the new 100s and the differences to the 39ers. It contains some pictures of a Senator Perpetual with a grey dial (however I cannot tell from the pictures if that sample it is SS or WG ):
Basel 2005 - new Senator cal 100This is all I can tell you. There are others around here who have a much more profound knowledge of matters.
Read you,
Martin