You hit the motherlode. Special???? You have got to be kidding! This is the bicycle equivalent of finding a genuine, virtually untouched, 1960s Shelby Cobra in a barn. Google [3rensho] and you'll start to realize what you have.
I just sent some 1984-85 3Rensho catalog scans to VeloBase; they're at
http://www.velobase.com/Resource_Too...alogScans.aspx. And go look at
http://vintage3rensholove.blogspot.com/. I sent the scans to Dave Hickey for his blog, too, and also sent him scans of the magazine reviews of 3Renshos from that time.
The SRA seatstays changed to full fastback on the later Katana.
Welcome to the 3Rensho owner's club!