Don't know where you could find a vin decoder, but if your interested in what options are included on your vous, there should be a sticker somewhere (glove box or hidden behind some panel cover someplace in vehicle) with RPO codes. Since you have a CXL this sticker should have
PCL on it (CXL option). For the other codes on sticker you can look here:
http://gm-trucks.com/home/content/view/198/30/