Hello, welcome to the SKS-Files.
You have a 1966 Chinese Type 56 carbine there. It was built in Chongqing at Jianshe Arsenal (which by this point in time was a amalgamation of previous arsenals [such as Arsenal 21, Arsenal 26, etc.] which had been moved from other areas to the relative safety of central China). The year 11 series contains the highest observed S/N in all of Type 56 production, topping out at a S/N over 590k.
Looks to be in a replacement stock and the carrier appears to have had some corrosion issues in the past. Scope mount is an aftermarket add-on. They are well built and good shooters.