I was looking for the same info. In another post it was mentioned that it is a special mix called super silver (Sherwin Williams JX-12224) with flattening agents in the clear when used in the interior. Someone tried to contact Bob from Sherwin Williams and it is no longer available. GT tech mentioned that they tried a bunch of different colors and he thought best match was Ford Aspen Silver.
I searched to find out more about Aspen Silver. It appears to be a 1994 FORD Probe color paint code = SM. I'm going to try to order some to see how it looks.
If anyone has more current information about a replacement for "super silver" please let us know...