How many 1966 ford thunderbirds were produced with a 428 Q code engine?

I own one with the first three vin numbers being 6y8, and I'm curious of the rarity.

Out of 64k, i'd say about 10% had the 428, maybe more. That would be over 6000, but only 700 Q convertibles were made.

The registry below would be able to tell you more.