HOW MANY OF THE 9 FINNED ROCKER COVERS WERE MADE IN 56 & 57

Unknown, except maybe by GM. Even the number of engines built. There were lot of them manufactured and never made it on a car. One guy wrote, who claimed to work there, Quote: "The cracked mold is bullshit. We made those covers at the Chevrolet-Bay City Plant in Bay City, MI. The line you see is from the parting line in the die getting worn from repeated disassembly and cleaning which took place after a build up of castiing metal on the die surface. After the quality of the casting would deteriorate to the point the covers would no longer pass inspection the die was disassembled and cleaned. After repeated scraping and polishing the parting line opened up and allowed molten metal to creep into the space between the die pieces before it cooled. It was never intended for this part to be in production for as long as it was. The demand for the covers exceeded everyones expectations and new dies were out of the question at that point." End Quote

3,462 V8 Corvettes were built in 1956, and how many high-performance V-8-powered Chevys were built from model year 1955-72 has never been tabulated, added up, or figured out. Evidently, official V-8 totals were not kept until about 1961-62. Were any of these various performance engines ever installed in other Chevrolets for engineering and evaluation purposes? Perhaps. 1955-60 full-size Chevrolet performance car numbers were lost in a corporate fire.

If interested, read this really good article; http://www.superchevy.com/features/sucp_0803_1956_chevy_corvette_performance_history/viewall.html