"SAMPLE" 1970 340 HP intake manifold number 3462848 rarity!

Most of us are aware of the performance benefits of the factory 3462848 cast iron intake manifold from 1970, right?

Well I have an NOS intake that was factory cast with the word "SAMPLE" on the runner beside the part number, and the so-called date code is 6-24-R !!! AND there isn't a "clock" marking for the time of production!

Has anybody ever seen anything like this?