Ford 9" rear tag ??

I've read no less than 7 different sites and can't find out what yr 9" I have. I do know it came out of Lincoln(69-74 ?) and it's a 9" with a 2.75 ratio, but I would really like to know what yr and what does WGC stand for ?
The tag reads: WGC 45 5BD
2.75 9 470C
Thanks for info.

 

my info is 72 town car, 2.75 non locker

 

Here ya go: http://www.fordification.com/tech/rearends_ford09.htm and
http://home.comcast.net/~petebre/maverick/FoMoCo_rear_ends.html and
http://www.enjenjo.com/9inch.html

 

http://www.fordification.com/tech/rearends_ford09.htm what 19fordy said