I'm not sure about the year, one book I have lists it as a 46.
I thought the RCA numbering system was first digit=year: 621, 630, 641 were 1946, 721 1947, 8TS30 8T243... 1948 and so on up till 1949 at least.
Perhaps this was the year of design but the model year could have been later?
The 1950's had a similar system outlined here:
http://antiqueradio.org/rca09.htm