Yup going to avtomats-in-action is the best way to learn the differences between the years. Lots of subtle things change, like the size of the welds on the rails, the style of rivet head, the muzzle break, pistol grip, handguards, and buttplate.
I wanted to build a year-matching Afghan-era AK-74N for my 1984 NSPU-1PN34 night vision scope - notice the replica Russian optics rail (from avtomats-in-action).
I searched all over the web and in a variety of books for photos of a 1984 to make sure I got the details right. I had Mario (at POHF) do the selector engraving and notches, and another vendor did the front trunnion engraving. This whole thing was built on one of those unfired all-matching Bulgarian AK-74 kits that came into the country a few years ago before any of the Russian AK-74 kits came in. Those Russian kits didn't have an orginal barrel, but this bulgy kit did. I did the rivet & assembly work and finishing. I gave it a very light scuffing to try to make it look like it had been handled a bit.
If you want to build an 82, you'll want to look for photos so you can make sure you're using the correct handguards: There's multiple variants for both the upper and lower. Notice this rifle has the non-vented and scalloped upper and lower handguards.
-Thirtycal