The YSG range consists of 4 models all launched in May 1988 and discontinued in 1990. They were for the Japanese domestic market only although it is known that a few came into the UK possibly by mistake. There is a full comparison of specs available at the end of this page. The models are designated the 1 the 2 the T1 and the T2. The 1 and the T1 had gold finish hardware the other two chrome. The T series have vintage pro bridges and the others TSG-1G (tunomatic style) bridges. Hence it is fairly easy to tell which model.
29th August 2019
I found some catalogue scans on the net here they are: