Very simple, it's not entirely correct because not all the tags were moved to the dipstick support in the 68 model year. My 68 is a late build, and the tag is on the intake manifold, and has been there from Day One. And, I have found other examples similar to mine. Although many were moved to the dipstick, not all were.I think you need to keep in mind that changes were often running changes that did not coordinate with the beginning of the model year. So, saying that the engine tag was located on the intake in 67 and that it was moved to the oil dipstick support in 68 doesn't mean every 68 model was impacted by that change.
I would be interested in knowing how it's not entirely correct that the engine tag was moved to the dipstick support in 68.