72 Chevy Nova SS used brake master cylinder stamping ID question

[RALLY]

I bought a used master cylinder off a original 72 Nova SS to have rebuilt and put on my 72 Nova SS because my original was missing when i purchased my Nova. Cast number reads 5470409 and the front small machined half moon flat surface is stamped CX. My question is what does the stamped CX mean? Is this correct for a 72 Nova? This master cylinder has a 72 date code, julian date 2070.