Based on the content it appears to be 93-94. Interestingly it mentions that they improved chassis torsional rigidity by 20%... not sure if that means between 90-93/94-96 or between their first crack at the design and the optimized condition. It also mentions that the design work on the pair of Cray II (100mflops/ea) supercomputers spanned 5 years. An online archive from the LA Times reports on the acquisition of these computers in 1985... Nissan cites "aerospace development" as their intended use :) My apologies if this is a repost! Enjoy!