Inland,
It is my understanding that all of the M1A1icon stocks, even the post-war replacements, were manufactured without the M2 cut. I couls sure be wrong about this. There is a ton of data on the WWII produced stocks, but not much that I can find on post-war or Korean-era SA replacement stocks.
Frank,
The gentleman I bought this from claims it is in fact a early 60s DCM sold stock. I have purchased some other parts from him. They are pristine. Additionally, he has a '62 released Winchester carbine that is right as rain, with the paperwork. In short, I have to believe him as he has been quite honest in my other dealings with him. I just wish I could find someone else who has a known/proven post-war replacement stock that was purchased from DCM on the early 60s also for comparison.