That's not the case since we have D port number 16 castings with the long exh air injection passage running above the Exh ports and without it, and you would have thought that with such a big change in the casting that the factory would have assigned a different casting number, but they did not.
The best explanation I have ever heard is that a certain number of 66 CC casting 48 heads went thru a abbreviated maching process of the chamber to get leave it at 66 CCs and not 72 , and these where to be used on the 350 HO option coming up in 69 that Pontiac had high hopes for sales wise.
When those big sales numbers did not come to pass then these heads where used on the manual transmission RAlll motors only!
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!
1) 1940s 100% silver 4 cup tea server set.
Two dry rotted 14 x 10 Micky Thompson slicks.
1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.
Education is what your left with once you forget things!
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