Did all the pre 68 383s have the bolt holes drilled and tapped for the A body mount?

I ask because I have a 67 383 with the holes drilled and tapped for the driver side mount.

I also have a 68 and a 69 block and there is a boss there but not drilled and tapped.

Just curious if maybe I have an A body 67 383 block but I thought I read somewhere that early c bodies used this weird mount too...

Anyone shed some light on this?

Dan

67 charger