Decode 440 block

What do you think the approximate date when 1972 model year car production began? It sure wasn't Jan 1 1972.

It was about July 1, 1971.

Please note it has an "H", as in H440, to denote model year, which is 1972.

1972 model year cars started showing up at dealerships in september 1971, IIRC. An engine built on 6/30/1972 would have been 99% sure to be a 1973 model year engine and would have a J code because those 73 model year cars would have begun production in early July 1972.