[poncho-mike]

I've seen missing numbers before on some 1971 parts. I have a single #96 head where the year digit was missing from the cast date.

I believe I have an explanation for why you would see missing numbers in a cast date. Since the cast date changes daily, the four digits of the cast date were probably put into the tooling as inserts so the casting facility could easily change the date.

That explanation doesn't hold for the intake. I would think the p/n would be a permanent part of the tool since it shouldn't change. The p/n would only be an insert if you expected it to change, so I would expect the entire number to be an insert in that case.

Mike