How can you confirm the shutter type? I have an older sx-70 (no split screen focus; SN 0J304150929).

Stamped inside the camera- XH3271B4P (on metal underneath near lens); J304ABA. Neither appear to have been changed or written over.

You have to double check the shutter shape as in the picture.
Serial Number :
0J304150929
Config :
hybrid "Q" shutter
Model :
Model 1 or Alpha 1 Plated
Birthday :
September 10, 1973
Camera Number :
41509
Shift Number :
B

I see, I'm not very mechanical so I was unsure how to check the aperture shape and was wondering if there was a way of checking the shutter label. If it was a camera you were looking for, I would be happy to lend it to you to examine for your research. You might also reach out to the owners of Polamad -- I believe they own, or at least did at one point, a very early SX-70 company "loaner".

Though upon reflection, considering the internal memo was from 1975 perhaps it pertains to cameras manufactured in a period just before the memo (?). It would seem odd to only address the R shutters after 2 years when they had already been doing other upgrades to early models earlier to my understanding (I believe customers could send in early models without the split screen viewfinder to get the split screen added). At this point it is very hard to find early cameras that weren't refurbished by OG Polaroid or another vendor in recent times.