According to the Ulsterbus timetablefrom 13/05/91 there was a servive 363 which operated between Queen's and Jordanstown. There were only a few departures each day 4-5 in each direction and I would guess that it was initially operated by a Busy Bus given the first "3" in the service number as it was a a time when town services operated by Busy Buses were being introduced, where the original service number had a "3" put in front of it)or relaced the first number.