the link in the above post if the PACSWI-x, i bought my SWI-2 from them before they came out with the -X, It was the best $$ i ever spent. Great service, fast shiping, and great prices.
If you want to read a funny story, here's how i found out about that site. I had a 92 bonneville, and nobody does anythign with those cars, i wanted to keep my steering wheel controls, so i searched the web, and after riding in a freinds TA, he had the same steering wheel. So i joined ls1.com (his car was a LT1, but i did notknow much about f-bodys at the time) Finally found info there on how to keep the controls, bought the part, and eventually bought a LS1 partly becasue of that site.
Most expensive stereo project ever
but lots more fun than a bonneville