Trans Case Date Code Question

Can anyone tell me what the casting code "1 1" means on this 4 speed trans up for auction on ebay? Thanks.
http://cgi.ebay.com/ebaymotors/Harley-K ... 336571d5e3

Case was cast in January 1951. In the fifties they used numbers for the month instead of letters like in the 40's.

Ralph,
Thanks. I thought that was probably it. I haven't been involved with anything newer than late 40's for over 30 years and back then I only cared if it fit in whatever frame I was using for the build.

For several years in the mid '50's the only code used was a 3-3.

Thanks Chris. I always learn something new on this board.