Re: 66 390cu Carb
You know, it's sad Pony Carburetors went under. They were THE source for rebuilt/restored Ford Carburetors. The correct carb. for the 66 390 was believe it or not a 460 cfm Autolite 4100. Same for the 428 too! I have no idea why they made the switch from the 600 cfm from previous years but they did. Holley did make a 460 cfm replacement 4160 carb, but you could replace it with a readily available 600 cfm 4160 carb., you'll just have to wire an electric choke.
Using Pony's handy carburetor guide, the correct Ford engineering part # for either the 66 T-Bird 390 or the 428, non-California (w/o Smog) is C6SF-A. This will be on the tag attached to the top front left corner of the carburetor, if still present. If not still present, all is not quite lost. On the left side of the carb., on the left front corner, will be the venturi size stamped. The number you will be looking for is 1.08. This means the carb. venturis are 1.08" diameter, indicating a 460 cfm unit. A similar engineering part # will also be found on the left front mounting ear, though abbreviated.
Master ASE Certified L1 Chrysler Technician- still a Ford fan at heart.
1964 Thunderbird Hardtop- Chantily Beige- 390 FE 4V V8-Uncle's Car
1966 Thunderbird Convertible- Red- 390 FE 4V V8- Uncle's other car- waiting for paint and body work!!!