Appears to be a rebuilt stock carb (autolite 1100 or 1101). You might try contacting RockAuto at the 800 number in the ebay listing to make sure it's correct for your application. If you have your original stock carb on your '66, it should be a 1.5" throttle bore, scv carb (important if you're still running the stock load-o-matic dizzy), so you want to replace it with similar if you're sticking with that set-up.
I think the C806 part number is an Autoline part number, not a Ford part number. Ford part number's for the autolites only had a number in the second place of the code for year model, and the other three digits were alpha characters and followed by a dash and another one or two alpha characters (eg C8OF-B).
My guess, this is one of your standard fare rebuilt 1100's...so it my have the potential drawbacks many mass rebuilt 1100's come with...namely deleted parts.
My two cents, you're better off rebuilding your own carb with a kit, being sure to replace any damaged or missing parts, or have Pony Carbs rebuild it for couple hundred dollars. IMO I believe that many mass rebuilders of the 1100 (ie Autoline, Cardone, even Holley) generally focus on quantity versus quality. To save time, they remove required parts like the fuel bowl vent rod and calibrate the carb to run at an idle rpm above correct setting (ie 1000+rpm). Then when you try to set the curb idle lower you discover the true quality of the rebuild, for better or worse.