I'll hesitate and say......1986, simply cause it was the first SKS to sport an Ak mag, I'd guess that based off the other Shotgun news ad you posted, it took maybe just about over a year for word to get to China....... "the gluttonous Americans love big fatty mags and short barrels on any rifle, especially cheap rifles"
. And, it took them that time to get working models and set up production.
But why it a Type 84? I know there is a Type 84s Ak, this ain't got nothing to do with that, I'd guess Navy Arms took 2yrs to create it, design started in 1984, release to public in 1986.. They slow, not like the puppy-monkey-babies at CAI..
Shut up GM, you ain't no where close..