3 of 63 was an Expanoid who helped create the alternate dimension version of Earth named "Twentica".
3 of 63 was generally on bad terms with his superior, 4 of 27. In the first meeting between the boys from the Dwarf and the Expanoids, 4 of 27 mentions that he is a true warrior and "highborn", nothing like that 3 of 63.
Much later, as the Dwarfers were about to be killed by the Expanoids in the Lady Be Good Club, the animosity between the two Expanoids was brought up by Dave Lister who remembered 4 of 27's ealier comments. Telling 3 of 63 that his boss had been slagging him off behind his back, 3 of 63 got angry with his boss, with his boss asking him to leave it and saying it was from a time things were not good between them.
The bickering between 4 of 27 and 3 of 63 gave Einstein Bob enough time to complete the handheld EMP weapon which would deactivate the Expanoids. (Twentica, Series XI)