Factory rivet on my AA import for comparison; plus stand alone.
Here is a Early .308 in the AR configuration; only 13 digits above yours that just sold not too long ago. Looks like the IMI mag. fits.
Yours is the first early I have seen in the ARM configuration.
I like how the early MR imports had the individual components serialized; which a few of mine have.
Still would like for you to take your hand guard off and see the date stamp on the barrel; which looks like it is blocked by it. I thinking 82'; maybe 81'.
You will not hurt anything taking it off carefully and you will be able to inspect your rifle closer; plus clean / oil in those spots.
Pics of ejector, barrel markings under the handguard, and bolt carrier. Gave her a detailed cleaning and oiling afterwards. Great shape, barely fired best I can tell. View attachment 30479View attachment 30480
Was perusing the Web and came across the ad below, which reminded me of this thread.
http://www.prebanarmory.com/rare-magnum-research-galil-ar-308/