The Miyata 1000LT was not offered in 58cm (color and decals match 1989, so I'm educated-guessing on the year). It was offered in 50, 54, 57, 60 and 63cm
Miyata Bicycle Catalogs: Miyata Catalog 1989
It came with a 3 x 7 or 21-speed drivetrain as standard.
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'75 Fuji S-10S bought new, 52k+ miles and still going!
'84 Univega Gran Tourismo
'84 Univega Viva Sport
'86 Miyata 710
'90 Schwinn Woodlands
Unknown brand MTB of questionable lineage aka 'Mutt Trail Bike'
Plus or minus a few others from time-to-time