1966, 11637 car 327/350hp ,engine code F0329ZI, I know the part number I need , was wondering on a date range . One or two before that max ? It had been replaced with a dual point from a corvette w/tach drive but the previous owner kept that.
I wasn't sure of the application...there are some bolt on parts that have specific dates because of batch production. I'm no expert on your era vehicle so I would guess the normal range of 1-3 months would apply. I would speculate the L79 parts were run in batches like the other years...perhaps another L79 owner with a "known original" part can share some info with you.
It could be before or after the block date. Our original 57 Bel Air parts car has a March dated block/heads, but an April Distributor and generator. It's a late April built car. The most important thing is that it's not too much earlier than the block, but more importantly, it's dated before the cars build date. Then it would be considered correct.
You really want to relate the date to the build date of the car, not the engine. Assuming this is a U.S. built car, you probably don't know exactly when it was built. The code at the top of your cowl tag (body build date) will give you an idea. It'll be something like 03D (March - 4th week). There are exceptions, but usually the production date of the car was soon after this. In Canada, GM documentation tells us exactly when cars were built. We find that parts dates vary, but generally are 1-3 months prior. As an example, my L79 was built Nov 26/65 and the carb was 3rd week of August/65.