Holley Carb ID

Locomotion said
Good point. If I remember correctly, the 780 had the standard downleg boosters. The subsequent 750 versions had the little "bar" across the booster which helped the vacuum signal but cost 30 cfm.

Yup, that's right so that makes it a 780. It sure looks old enough.

Why somebody would do that to such a valuable carburetor is beyond me. They only came on factory applications.