That number is based on researching the invoices at Schmeller Aluminum foundry as that was the company originally casting the dual quad intake manifold for FoMoCo.  Here’s an older link regarding on the subject.
http://forums.y-blocksforever.com/FindPost64116.aspx

Lorena, Texas (South of Waco)

Also keep in mind that intakes produced probably does not equal E code cars produced.



Lawrenceville, GA

But does it mean there were no more than 5500 E-code cars total, T'bird and passenger cars included?
Seems to depend on the reliability of the 5500 number and the degree of certainty there were no other suppliers of the 2x4 intake.

Whatever the number of intakes produced is, cars produced must be less than or equal to that number.



Lawrenceville, GA

While it has been confirmed that there were ~5500 1957 ECG-D dual quad intakes actually cast, it can be assumed that a given number of those manifolds did not go on the cars but instead were for over-the-counter sales.  It would be a stretch to think that 10% of those manifolds were for over-the-counter sales but with no documentation on either the number of cars actually equipped with dual quads or the number that went to parts counter sales, then 4950-5000 cars actually being factory equipped with dual quads would be a starting estimate.

Lorena, Texas (South of Waco)

Thank you, Ted. If we trust the estimates that there were approximately 1400-1500 E-code T'birds, that means roughly 3500 E-code passenger cars. Since I happen to own one, I've always sought to quantify its rarity. This may be as close as I'll ever get. 

Ted - One quick follow-up: Who possesses or has counted the ~5500 invoices you mention? 

That information looks to have come from Dennis K about 14 yrs ago.  Here’s the link to that reference.
http://forums.y-blocksforever.com/FindPost64116.aspx

Lorena, Texas (South of Waco)

____________________________

Kultulz - Just to clarify, the invoices in question here are Schmeller Aluminum Foundry invoices for the dual quad intakes cast for the 270 HP engines.