There are around 3 or 4 flexplates setup. Not only the size is the difference like also one of the crank bolts is on a diff position ( offset ) than the other ones

Dunno if the offset bolt at crank is for 6 cilinders, SB or BB but is afact it does exist.

Diameter for stock converters I think is 11 3/4" and 10 3/4". Some Hemis got the larger ones in fact

With a Charger born in Chrysler assembly plant in Valencia, Venezuela