Both are Tula. The beveled one (the one on the right in the first picture) is the early one, and the one on the left is the late one.
I'm not exactly sure what year the change happened. The '86 kits still had the early one, and I have several pictures of '89 guns that have the late era one. I haven't found any pictures of an '87, and the few I have of an '88 show the late era one but I'd need more examples to be sure it wasn't just changed out after leaving the factory. Hopefully Tantal/Jithaca can chime in.
If I had to guess, I'd say the change occurred in 1988. The few pictures I have show alot of the late era features of the AKSU had shown up by 1988. It's really hard to tell since I haven't found any pictures of an '87 though.
Both seem to have the same value usually when I see them go up for sale. Hope that helps