Big blocks at the Tonawanda engine plant 1969

[Ralph Spears]

Those are cast iron bell housings in the last group of pictures. What year did they start using aluminum.

[John Brown]

Those particular big blocks pictured just above are most likely BFT engines because of the bellhousings attached. The black exhaust manifolds are likely those found on BFT's and school busses too, and not a representation of what was used on normal passenger cars.

[RPOLS3]

Those bellhousings look like truck applications?

[Kurt S]

I obtained and used those photos in the Assembly article.
The titles are with the pics. Specifically, the Life magazine pic is:
Engines As Received (at Tarrytown Assembly Plant, 1959)
http://www.camaros.org/assemblyprocess.shtml#engine

[John Brown]

After looking at the 1970 dated Flint big block picture once more, the intake manifolds show dual thermostat upper outlet. Definitely BFT stuff.