Welcome to the group samc.
I use a mid 70's 10-3 as my everyday work carry.
It is mid 70's because of the old style handle shape (Rosewood) and the Randall stamp is straight across. The angled stamp came in Mid-late 70's.
By the way, I don't use the original sheath pictured with the knife, I use a sheath made for it offered on eBay, secondary market.
Regards, Sam