I have the engine out of my car, and was planning on painting it before re-installing it, so I used a wire cup brush to get some of the loose paint off. As I did, some yellow markings became visible. JohnZ told me (over at camaros.net) that it was usually the suffix code for the motor written upside down on the block as it went down the line. I was told that the motor was bought as a short block over the counter, so there's nothing stamped on the front pad. Anyway, here are a couple of pics, tell me what you think. The drivers side will need some more work to be able to see the writing, but there's something there as well.