There is about 4 times more stampings than you have listed. You only have a partial list. The factory stamping has less intellectual value than one would think. The Chinese doctrine for producing firearms was that the parts were made one at a time from many different factories. One factory made sights, the next factory made stocks, another made only barrels, ect.
The Chinese did this in a manner of producing no "lost" materials and consequently no lost or missing firearms. Any and All Chinese SKS came from a multiple of factories. The factory stamp tells little more about the rifle other than where the receiver was manufactured.