The gentleman has it wrong regarding the Z-11. There was no such thing as a Z-11 for 62. RPO Z-11 was for the 1963 model year only. As a matter of fact the Special Service Package of parts with the 2 piece intake manifold and valley cover were different between the parts release for 1962 compared to 1963. Below you can see the 1962 version on the left and the RPO Z-11 on the right.
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In 1962 we know there were somewhere between 18-20 cars built with the aluminum front ends. Those cars had the 409/409 engine not the Z-11 which was a 427 cu in.
Somewhere I have a copy of the newspaper ad from Don Steves Chevrolet with 2 of the cars with the aluminum front ends for sale and I will post it also.
What Chevrolet did was to ship the parts to the drag racers of the day and never built a car with both the aluminum front end and the Special Service Package parts that eventually included the 2 piece intake. It should also be noted that there were many releases of various combinations of cams, springs, heads, etc as Chevrolet strived to get the proper combination that would allow them to win at Indy in 62, that was the goal. Our friend Hayden Proffitt was the one that did it!!
I have validated this info from 2 pretty good sources, Hayden Proffitt whom we all know and respect and Dick Harrells wrench, Charlie Gaines. Both told me the cars they built, they did so with parts shipped to them. Hayden and Charlie both told me they received the heads and engine parts in one crate and a few days or a week later the aluminum front end parts came in a larger crate.
I hope this helps someway.
Pat