...AND '58 312 Mercs have ECZ-G cylinder heads that are posted!   
However, while the 312 was the base engine for the '58, '59, and '60 Mercs, the last year for the Mercury factory installing the 4 barrel manifold and carb was '57 according to my books.   

NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Thank you Ted ..  Im going to look at a "312"?  that's from a 58 Mercury and was unsure..   Steve McD

Mars , Pennsylvania

Part numbers for the 312 blocks and 4V intakes are shared by both Ford and Mercury.

Lorena, Texas (South of Waco)

Are the 1957 and later Mercury 312  Intake Manifolds the same part #  [ECZ-B]   as there Ford counterpart  or are they a different number ?   Are the blocks a different number ?   Thanks Steve McD

Mars , Pennsylvania