Re: Yamaha SJ 180 -- all
I've been shopping for used Yamaha guitars for my two boys and have gathered too much information, I hope is can be of help to some.
The SJ180 was built by Yamaha from 1981 - 1985, $210 MSRP ($495 in today's dollars), spruce laminate top, rosewood fingerboard and bridge, mahogany elsewhere, TM-15 tuners, SJ => semi jumbo. The top-of-the-line SJ model back then was the solid-top SJ400s ($370 MSRP). They both joined the Folk series in 1981. Yamaha made their guitars in Taiwan PRC during this time.
I've heard that Yamaha added truss rods for easy neck setup during this era, look inside at the heel and see if there is a visible hole with hardware in it. My boys now have two beautiful, soulful FGs from this era, they both have truss rods and the neck setup only cost me $70 each. My pre-truss-rod Martin recently cost me $600 for neck setup by factory a authorized luthier.