Your 84s should be stamped. The easy way to tell is if the receiver has dimples stamped into the side right above where the magazine goes. Milled recievers are milled from a block of metal, and will look that way. Stamped are stamped from a flat sheet and look that way. You'll notice on your's that not only the dimples, but the corners where the floor turns into walls is obviously bent to form that, and not machined from a block.
All the .223 Norincos are stamped by the way. Both your pre-ban 84s, the post-ban Mak-90s, and the post-ban BWK-92. They're all the same gun, just different time frames imported. They also take all the same mags, and are the best .223 AK for the money. I suppose the Galil or Valmet is better made, but you won't find them for what you payed for the Norinco.
I've had a 84s and still have a Mak-90 .223 and I wouldn't hesitate to buy another over a SAR-3 any day.
Ross