I've spent the weekend going back through all my old Traveller books looking at the uniforms that were drawn by different artists. The Imperial Army and Navy seem to have the same BDU if you look in the Rebellion Sourcebook (pg. 41, 93, 94 by T. Peters-Navy uniforms) and p.57 by Danforth(Army Uniforms).
Also, on pages 7 and 18 of the Arrival Vengeance adventure supplement. These are all b&w drawings and no hint to what uniform color they have. From Arrival Vengeance, I'm guessing that the Navy Uniform is a dary grey in color. These uniforms I think could be used as emergency vacc suits with the addition of gloves, portible life support system, and a helmet (items not yet shown, but some system similar to what is being shown on the new Battlestar Galactica TV program for it's Viper Pilots. A removible neckring to which a helmet is later attached).