Those questions are confusing.??(between stock upper and the Large) What is actually different between them?......They look taller than a stock upper as well.
For what your calling a "large upper" do you mean the ones that are the same length but the hieght & width is larger?
If that's what you mean, then I think your thinking of a MAC10, these are in 45acp and they are the only ones I've seen like this. The M11 (9mm) & M12 (.380) are the same size. OK I just found out the M10 was also in 9mm, here look at this link it might help.
Modern Firearms - Ingram MAC Model 10 / M10 and Model 11 / M11 submachine gun