Commonly known as plant codes. I have read they where used to get the right carb on the right car. And simplified plant workers from looking at actual part number. (2 letters vs. 7 numbers) I believe that code is included on build sheets. That I know of there is no 'list' out there that will decode these. There are a few out there that have been doing Quads for a long time. And have taken the time to record all their findings when they know a certain carb came off original documented cars. They do guard this info pretty closely due to all kinds of riff raff out there that would use those codes to 'restamp' normal carbs into high buck rare units. Seeing that example carbs app. is a 'basic' 72 Buick 350 non California. Would guess it is not a rare unit.
