I know that it is stamped September 5th 1969 (thats the year of the Chevelle) in Buffalo, New York. But what does the CN mean?

That tells you what ratio it was originally equipped with, and whether or not it's a posi. Don't have my book with me now or else I could get the info for you - sorry....

I think i may have answered my own question. 273 non-posi is the decoding that i'm getting. Chime in if you think i'm mistaken please.

CN is a 2:56 Open rearend code.

http://chevelles.com/years/69/69rearcodes.html

Great link, Dean, all these years here and I had no idea that axle codes were listed on this site :clonk: