That's a rumor. VIN stamping did not start until the '68 model year. There was a lot of debate about this over at the Classical Pontiac site and a poll was taken. Nobody with a '67 block could find a VIN.
My "numbers matching" '67 400 was built in June '67 and the YT block has no VIN stamping.
Diesel: If you car has an auto transmission (and it should be a Turbo 400) it will have a stamped YT block code on the upper right front of the block. Manual cars were either WZ or WU codes.
Unless you happen to have one of the 60 or so Ram Air I's.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI