This might come in handy, since it includes better exploded views than the typical GM parts sites. Enter the year or VIN and you're on your way! It not only has a more detailed (and larger) view of the parts, but it shows the part numbers as well, including superceded, upgraded part numbers. The prices seem to be comparable to the other online sites as well.

http://www.gmpartsgiant.com/cadillac-xlr-parts.html

CC :cheers