how would I find out what radio my Cougar originally had? Mine's pretty basic, so I know it was one of the lower end radios.
My mom found out some stuff with her 85 tbird by having the vin number ran, I think she actually called a ford 800 number and talked with someone.
Ford used to offer what was called a 999 Report at no charge by calling an 800 number, however that service is no longer available for free.
They have changed the name of the report to "Build Sheet" and they now charge a fee for the service.
There are also two styles available now. A "Basic", currently priced at $17.00; and a "Deluxe" that also includes production figures for $40.00.
Go to http://www.shopfordgear.com and in the search box at the top, enter "build sheet".
I will forewarn you about spending the extra money on the Deluxe report. Currently the only production figures that are provided on the Deluxe report for our cars are the total production for the entire line. That's quite a premium for only one extra line of information.
Examples of Basic and Deluxe reports.

For a FREE option, enter your VIN at this site: http://www.decodethis.com/
My dealings with Ford, read before you buy......
http://www.foxtbirdcougarforums.com/showthread.php?32319-My-FORD-999-report-came-today-1983-Thunderbird&highlight=999