Velocity stack question. Can anyone help?

I bought a couple of really nice, older aluminum velocity stacks recently. but the end that mounts to the carb is 6 inches in diameter. I thought most carbs had a 5 1/8 hole.

Anyone know what application these would be for? They have the screen and mounting hole in the bottom as well, but no manufacture stamp. They are not the cheap kind, but look really well made.

Thanks in advance, Cam

 

holley dominator carbs probably