Need thoughts from the database experts on my [0138]'s SN

[Greatguns]

Okay, I posted about this rifle before concerning the crack in the stock and the repair I made. I was thinking about selling it and in the process of looking through my pics on it I realized something is different about the SN. It is a 7M SN on a rectangle arsenal followed by a 4. This means it could be a 7M SN or a '74 prefix on the SN, neither of which seem to appear in the SKS guide database that I can see. Definitely on the "Dating the Chinese SKS" page, unless I am totally missing it. As an FYI, it is a short collar threaded barrel
Any thoughts?

[Phosphorus32]

1974 

Look in the serial number data and you'll see this format is common for [0138]

https://sks-files.com/index.php?topic=393.0

[Greatguns]

Okay, I figured that's probably what it was, but now I am left asking myself "how in heck did I miss that in the database threads?"

That SN is even listed in the format(all but the x). Sometimes I live to embarrass myself, LOL.

[Phosphorus32]

That SN is even listed in the format(all but the x). Sometimes I live to embarrass myself, LOL.

Nah, it's just that you have so much knowledge that a bit leaks out sometimes 

[Greatguns]

That SN is even listed in the format(all but the x). Sometimes I live to embarrass myself, LOL.

Nah, it's just that you have so much knowledge that a bit leaks out sometimes 

Either that or I put it on a back burner and forgot to turn the burner off so it fried.

[Larry D.]

Either that or I put it on a back burner and forgot to turn the burner off so it fried.

Happens to me all the time.

[lowell66dart]

I kike to tell people that I can't always remember what I actually know.

[Larry D.]

I kike to tell people that I can't always remember what I actually know.

That would make a good sig line.