You need the history of the car. I don't remember the web site or phone #, but its a GM data base. other members may know?
Here are some links to help you get started.
Jason's body name plate decoded: http://6364cadillac.ning.com/profiles/blogs/body-name-plate
GM Heritage Center - Cadillac Data Books: https://www.gmheritagecenter.com/gm-heritage-archive/vehicle-inform...
GM Media Archive: http://www.gmmediaarchive.com/
The VIN # will give you the Year, Body Style and Production # for the year.
Click Here for decode of the VIN
The Body name plate will give you additional information such as Paint Color, Top Color (if different), Interior Trim Colors and Options, accessories, production #'s for that particular body style, Month and Week produced, etc.
Click Here for that link again provided by Josh.
The GM Heritage Center can provide the Build List which has additional information about the car. They also send low res scans of the Data Books and Specification Manuals (if you want to deep dive into you year I would advise finding a good original copy of these books). You can access the data books, spec manuals, etc on the GM Heritage Center site.
Here are the two main links:
GM Heritage Center (for build list, spec manual, etc, for your car)
GM Heritage Info Packets (data book, spec manual, owners manual, ama specs)
Click Here for the direct link to the 1963 Cadillac Information Kit (Low Res scans referred to above).
Thanks alot... it looks to be very usefull indeed