Quote-Went back in my E-mails and here's what I found out.

67-68 used the MC 2225541. Had a 1" bore. Was used on both power and manual disc brakes. The MC lid had 70R3 stamping.
67-70

69-70 used MC 2229171 and 2229191 which was used on the Hemi cars. The lid had a stamping of J1703
2229171 (1" bore) was '70 E body disc except hemi
2229191 (1-1/8" bore) was all 70-71 hemi cars with disc

It's my understanding that the 2229171 was used on all disc brake cars through 1975.
70 E body only. The casting number 3461187 (1-1/32") master cylinder was sort of a 1 size fits all for most 71-75 power disc brake Mopars

Also 70-71 Cuda/Challanger used 294444476 and 477.
2944476 is the Chrysler part number for the 2229191 casting number 70-71 hemi disc brake master.
2944477 is the part number for the 2226821 casting number (1-1/8") bore master cylinder for non hemi power disc brake '70 B bodies

Of course we all know the assembly workers used whatever part was available on a given day.

I doubt a safety critical item like a master cylinder would be substituted at will by an assembly line worker without engineering approval. Not saying something like that never happened, there is a road test of a hemi cuda in a fall of '69 car magazine I've seen, and the underhood photo in the article you can see a '68-'69 C body disc brake master cylinder is what is on the car. Obviously the car would have been an early production car, but was that master cylinder installed on the line, or did the original master cylinder go bad shortly after the car started getting thrashed by magazine editors and replaced with what mechanics had available?