The X3 wasnt introduced until late 2006/early 2007 and was usually worked by whatever Washington had spare inc initially the Sxxx OFT Olympians as well as a Solo for a short working between The Galleries and Houghton.
DAF's, the acquired Darts and the last remaining Delta were also used. It tended to work alone and then it began to interwork with the X4 when that was introduced.
I can never remember the Omnicities on them and to be honest, they probably would have been away to the other depots by that point.
RE: Go North East