Interestingly that frame looks identical to two of my old frames i.e. an 85 Raleigh Maverick and a 85 Muddy Fox Monarch. Both made at the Araya factory, I'd be very suprised if this wasn't made their too.
I am cleaning up my 83 Stumpy. I've owned since new. I rode it a lot for the 1st 25 years. I think I misplaced a bushing/spacer that sits between the rear derailer and the drop out hanger. Can any one confirm i am missing it and have a photo of one. Thanks