Didn´t the A880 have an underslung neck, like the T880 did? Could it be an A800 (unless it really is an A500)?In post five, the OP wrote that the horn was purchased new in 1989. The AW01 (the issue has pretty much been settled in other posts in this thread) has only been on the market for a few years, so this horn would not be an AW01.
I bought a new Yanagisawa A880 in about 1987 or '88 and it was similar to the one shown by the OP. The one in the OP's photos has what appears to be double arms on the lower bell-pads-cups. Assuming the OP's horn was news-stock when he bought it, I'm guessing the model is an 880 like the one I bought in the late 1980's. DAVE