['ol Pinion head]

at least a dozen times.
have also ran across two smog era 400's & 3 originally installed 455 HO engines which had no confidential VIN stampee on them. keep in mind, I pulled a crazy amt of 400's & 455's from the mid 80's up into the mid 00's.

first occasion, I can remember on a notable Pontiac engine was near 40 years ago with a '70 YZ 400 which I bought as a runner, carb to pan. The partial VIN gang stamp was stamped at an angle with the last few digits, so lightly stamped, they were not discernible. Next to that string of numbers was another stamping. That what I assume was the later stamping, the last few digits were more legible, but the top of the characters were light stamped. The original PQ mated to that late May '70 cast YZ, shared the same partial VIN, but also had two barely legible characters at the end.

Have also had two Pontiac blocks, that instead of a pair of kinda parallel stamped partial VINs, the stamping of one partial VIN was stamped at an angle over top of the original partial VIN. This left one character in the middle of the string, hard to read without a magnifying glass.