Googled a old GM product number and this site popped up with the product number showing in various GM old catalogs.
This site would be great for cross references to see if the same part was used in other GM automobiles.
In the top left corner you can search a product number and picking the information source you select in each box.
If you press browse you can look in the existing cataloges they have listed
gmpartswiki.com
-- Edited by Greaser on Wednesday 1st of May 2013 01:04:41 PM
Greaser - https://en.wikipedia.org/wiki/Greaser_(subculture)
1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)