Certainly a frankengun there, do any of the parts other than the magazine and TG match?
The stock with that notch on the left side is most certainly off a gun with a rail (maybe a PU mount gun, coincidentally AAI was also the main importer of the PU mount guns.):
Or more likely a Navy Arms type 89 rail because the cut is pretty short:
I see no tapped holes in the receiver, so this gun it appears never had any mount installed. Could be a bubba assembled stock, could have been an extra stock the distributor slapped on because it was in better shape than what came from China, or could have come this way directly from the refurb shop that last touched it before export. It wasn't born that way though.
The S/N format is seen in late 'commercial' scrub/restamp. I have some others in my files that are similar:
This gun had a different S/N when it was 'born'. It likely had a different bayonet too as that blade doesn't look like it's hanging quite right. Is the stock ferrule cutout a "U" shape ora "V" shape?
I have no idea on the stock stamp, never seen it before. Where is that stamp located?