According to the Yamaha Archives there were two models. The SA30 released June 1968 at ¥33,000 and an SA30T released July
that year at ¥35,000. The obvious thought is that the T is the trem model and the other the non trem model.
Indeed that's what the archives say but they have been wrong before.
In general the main specifications appear to be the same.
Sean TheSupposedStringMeister has some details about interesting variations on the SA with "fake" F holes these are guitars with
the non trem bridge. See details on Sean's site link is
Odd SA30s
Quote from Sean on the T designation
I have a hunch the T stands for Thumbnail fret marker. That would explain the higher price as the SA-30(T) model has
fretboard binding and a more elaborate marker inlay. The 'ordinary' SA-30 has dots and no fretboard binding.
Specifications
Body Maple* with a high Gloss Polyurethane finish Celluloid (Ivoroid) binding with 2 similarly bound F holes
Neck Maple Glued in Matching on the Red and Green Black on the Sunburst
Fretboard Rosewood 22 Frets with a zero fret dot markers on the 30, thumb type markers on the T 630mm scale 13.75" radius
Headstock See pictures Matching on the Red and Green Black on the Sunburst Yamaha written on Aluminium Truss Rod cover with Tuning Fork logo
Tuners Yamaha Open High Ratio
Pickups 2 Hum Free Yamaha Anisotrophic Ferrite with fully adjustable pole pieces
Controls 1 Volume 1 Tone 1 Blender and a 3 way
Nut 43mms (by my measurement)
Hardware Chrome
Bridge Roller type strings individually height adjustable and bridge adjustable with Feather Touch Yamaha Trem
Pickguard Small black although an awful lot you see have either had them removed or didn't start with one.
Colours Sunburst, Aruba Green or Cherry Red
Years available 1968 to 1972
Weight 3.2 kgs
*Sources say some are Sycamore but unconfirmed I suspect Sycamore would only be used on Natural finishes.
Sharpened Flat sold one that they say is Maple and Beech
** There appear to be some hardtail ones about.