I don't recognised the serial format, so based on that and the AC9 start I'd take a guess it could have been made in 1999. If so, that opens up more possibilies as there were more aluminium models in the range by then (Arrowhead, Terramoto etc.)
I mainly ride 175 mm cranks. I have some 180 mm to try, but I haven't actually fitted them to a bike. I have one bike with 172.5 mm where I notice the difference, but I'm used to it now. I've previously had come bikes with 170 mm fitted and it I rode them a decent distance I'd start to get a...
I asked the seller about a frame number, but they are out the country at the moment and thinks when they checked before the paint was too thick to read it.
If someone on here gets it, I would be interested to know the format. I think it might be four digit, rather than a classic Toyo format...
The frame for the 1989 is pretty special. Someone can correct me if I've got this wrong, but I'm pretty sure it was fillet brazed by Masaaki Ishigaki (founder of Toyo).