Cylinder head date code ?

[73440]

Pulled the valve cover to confirm cylinder head casting number and am wondering if the other number is a 10,000 day calenders date code or is it a day / year code ?
The 10,000 seems more plausible with block date and casting numbers.
Haven't found head date code info in MMC Detroit Body of Knowledge book.

[6bblgt]

cast # 2406516

date code 02155 = 02/15/65

1965 big block 361/383/413/426

[73440]

Thank you @6bblgt .
Hmm, on a 440 2536430-6 block cast 10-3-67.

Who knows the changes thru the years.

[Chryco Psycho]

Most people hate those castings , install big valves & hardened seats , do some port work & they mae a lot of power , they are closed chamber heads & are great for making quench !

[73440]

Thank you @Chryco Psycho .
Sounds like they have some good attributes, just need some upgrades to realize their full potential.