Take the Prom out and look at it. The stock chip is usually labeled with a silver sticker including the call letters AXCA. If you have the factory recall chip, the silver sticker should be labelled BBKJ.
If you look at the #'s codes impreinted on the chip itself, you could find any number of codes depending on what company was sourcing chips to the maker of your factory chip when GM obtained it. However, you will always see the code "2732" included on the chip itself.
There is a 99% chance that the chip in there is a correct chip if it has the silver sticker with the word "DELCO" on it and the call letters listed above.
If you have a scan tool, the internal PROM ID is 0144.
That's the whole story as far as you need to know. If the sticker is any other color or is missing the DELCO sticker, it is aftermarket.
