According to a guide put together by a fairly knowledgeable member over at ARF.com, the 8,000,xxx range guns are primarily export / police / contract guns. He stated the highest SN# on a transferable gun was in the 8,002,xxx range.
Another member who owned one in the 8,002,xxx range stated he was informed his was mfd. in Nov. of '85...... I'd have to guess 1984-85 .
Do you have the link for that guide? Not sure they went in sequence by date of mfg... Saw a couple of 8003xxx range transferables and one 8113xxx that was supposedly a transferable 20" HBAR - over at arfcom.
Here ya go.....TonyK and Ekie put it together....
https://www.ar15.com/forums/Armory/Serial-number-info-on-Colt-factory-M16s-UPDATED-5-12-2013-/23-199902/?page=1
Keep in mind....there are lots of ...shall we say...."interesting" A2's floating around with serial #'s that are normally found in the M16A1 range
One poster mentioned in the thread he had a transferable A2 HBAR in the 8,021,xxx range that was made in 11/85 as well