Transmission ID

I have a 4 speed trans in my current Pan and I'd like to know when the trans case was cast. The part number is stamped 121-35. There is also a 1E stamped, not sure what that means. Finally, there is a little raised area that looks like a number plate was attached to the mold when casting and this raised area has a "3 3" on it. Am I right in reading the "3 3" as a March, 1953 casting date?

The 3 3 code was used for many years during the mid '50's. No explanation why.
Here is a thread about it from CAIMAG.com.
http://www.caimag.com/forum/showthread. ... +date+code