I was wondering this when I got mine as I thought the 88 white Courier was the first one. I suspect 83 has to be the earliest as if you look through the Araya range you can see there aren't many MTB specific parts, everything seems to have been begged, borrowed, stolen from various manufacturers i.e. Suzue BMX hubs, Araya cruiser rims, cheap touring bike cranks plus a smorgasboard of Suntour/Dia Compe bits and pieces.
The frame as I said before is identical to the Raleigh Maverick frames of the same period, probably made in the Japanese Raleigh plant. Quite a chunky frame with steel lugs as per old 50's rod-brake bikes. The seat stays are welded to the seat tube with a touch weld. You can see that it was the fashionable mountain bike Reepack look that they were going for rather than an offroad thoroughbread.
That said, I like mine a lot, it really puts a smile on my face whenever I ride it. Yours is very interesting too, especially the decals. Not too sure about that chainset, I know it's originla but I'd be tempted to put an old Stronglight tripple on there.