Mystery bump on bell housings

[rotorwrench]

It's appears to be an unfinished boss. It could have been for a bolt to attach something there but I have no information other than that there were different castings for the early multi-plate clutch and associated transmission. There may have been other changes to the bell housing design that I'm not aware of. I don't know if the right hand drive vehicles used it for some purpose or not but Ford put it there for some reason. Maybe someone else has more information.