Originally Posted by T-Mar
The SunTour letter codes are year-month. The general consensus is that the 1st letter represents the year, where A = 1984 and you proceed backwards or forwards from there. The 2nd letter is the month, where A= January. Please note that there is a minority, myself included, who believe that A = 1985, which would make your cranks July 1991.
SunTour themselves did not make cranksets. Traditionally, their cranksets had been made by Sugino, who were a member of the JEX trade group, along with SunTour. However, in 1990 SunTour was purchased by Mori who also owned SR (Sakae Ringyo). I suspect that SR may be the manufacturer of your crankset. SR used an open format date code, which would explain why your chainrings are double coded, 91 GG. If your crankset is indeed manufactured by SR, it would seem to put a nail in the coffin as to which interpretation of the SunTour codes is correct.
Thanks T-Mar, that explains it. Now I see why you say '90-'91. I looked for a review of the Project 7 today, but the closest I could find was a '91 Project 5 review, and a '90 Grizzly review. The '90 and the '91 Bianchis both had the same decals my Project 7 has, so I didn't narrow things down any further that way. I think, based on the 91 GG code, I'm going to assume it's a '91.
Your reasoning on the date codes for SR makes a lot of sense to me.
Thanks again!