According to page 10 in this manual
968 manual
Here are the color codes by year: (no year means all three years)
908 Grand Prix White
38B Maritime Blue - 93
22R Mint Green - 93
700 Black
719 Black - 93
82N rubystone red - 92
22S signal green - 93
80K guards red
12G speed yellow - 93
39E riviera blue - 94
39D amaranth violet - 94
39A amazon green metallic - 93
38A amethyst metallic - 93
37U cobalt blue metallic - 93
82H coral red metallic - 92
37W midnight blue metallic
37X horizon blue metallic - 93
35V marine blue metallic - 92
738 black-metallic - 92
746 black-metallic - 93
22D slate grey metallic
92E polar silver metallic - 93
22L oak green metallic - 93
83E raspberry red metallic - 93
23I wimbledon green metallic - 93
37E violet blue metallic - 93
39N iris blue metalli - 94
39R aventurine green metallic - 94
According to this - 37W midnight blue metallic was available all three years.
But here's some other shades of blue available to you in 93:
38B Maritime Blue - 93
37U cobalt blue metallic - 93
37X horizon blue metallic - 93
37E violet blue metallic - 93
So bottom line is it's probably 37W, but MIGHT be the other four available blues.