Introduced sometime in the early 1970s, the 5021 was an acoustic dreadnought style 12 string guitar, with a solid spruce top bound with w-b-w-b-w-b top purfling and black pickguard. The round sound hole had an attractive synthetic shell rosette.
It had a rosewood fingerboard with pearl dots (some later versions had a bird wing inlay at the 12th fret).
I took it and had it cleaned up a few times over the years, just to keep it in it's excellent shape.
I am considering selling it, for I feel like it's beauty is being wasted. My 1990 Alvarez 5021 12-string has a solid spruce top as far as I can tell by looking at the edge of the sound hole. I specifically insisted on a solid top 12-string of a good name brand when I was shopping for it. Stays in tune remarkably well over time for a 12 string.
The guitar appears to be in very good condition, and based on this and what other Model 5058s are selling for, it is currently valued between $400 and $500.
This is a unique instrument with limited applications based on the string layout (although Alvarez product literature indicates it can be played as a 6-string as well), and they were only produced for a few years.
While most regular Alvarez acoustic guitars are built in China today, the Yairi line is still handcrafted in Japan.
Alvarez uses a numbering system to identify its guitars (although some also have a model name), and from the 1970s through the 1990s, this was a four-digit number—which falls in line with your guitar model of 5058.
Some users have noted that the unbalanced string layout causes the neck to twist because of the added tension on the treble side.
Astute readers may also notice that the same layout of a 9-string guitar can be achieved by removing the three bottom octave strings of a more common 12-string.
According to information on the inside of my guitar, it was made October 22, 1980 (22-10-80), it is a solid spruce top with rosewood back, sides, and fretboard, and a mahogany neck. Am looking to get a Rickenbacker electric 12 string now.