Looks like your choices are 'oak', 'pewter' and 'cashmere'. These differ from the actual trim designations, which were described as 'medium pewter', 'very dark pewter', etc.
Here's a dealer link which shows the choices - and while the link references a North Face, I believe they had the same interior color choices as the other trim levels:
http://parts.royaloakschevy.com/a/C...HFACE-EDITION-Y92/041021TS16-263TS16-263.html
It looks like the color codes for pewter interior for 2002-2004 were 92I and 95I , FWIW
If you really are replacing the whole carpet, you should be able to get pretty close with an aftermarket replacement - for example:
http://www.stockinteriors.com/AutoCarpet.asp?Itemid=17898&MakeId=31&ModelId=634
If you click on the 'Samples' link at the above site, there's no 'pewter' listed - but it looks like a couple of shades of grey are close.
You could also look at this as an opportunity - to have something unique, with a color that would contrast nicely with your trim / seats, etc., but wasn't offered as an OEM option. Especially if you decide to get something a little more 'deluxe' / plush over OEM quality.