440 4spd question

So does it REALLY matter if i use a tranny with a smaller retainer than the opening on the bellhousing.???

If it is a problem, Can I buy a new retainer for the tranny that is the same size as the round opening on the bellhousing.

Do you guys understand this???](*,)

i thought I have found a bell housing from someone on this site, But I don't want to buy a bellhousing that I can't use again. It is one of the casting # that I know works for this conversion. I am just haveing problems mentioned above with it.