date coded parts from factory installed- Nova 72- Help?

[RALLY]

Does anyone know how Chevy built cars on assembly line with the correct date coded parts. My 72 Nova was built in the second week in Feb and when i purchased this car had the original alternator missing. I found one to buy, but hesitate because the date code on the alternator is Jan-6-72. This being said its a month date coded earlier than my Nova was built. Would this be correct or alright to buy and installed seeing the date code is earlier by a month. Any help input is greatly appreciated.