What year is my Wicked Fat Chance?

I bought this used about 10 years ago, but never really rode it. Finally fixing it up, seems to be pretty intact. Pretty cool bike really, reminds me of my 90 stumpjumper only nicer.

Anyhow, based on the fact that it's a 7sp XT bike, I'm guessing it's from 90-92, but I'm wondering if there's any logic to the serial number: 031W09.

Thanks!