I'm not sure then but according to the changes on the link above it says:
Service X2 - Will be withdrawn and replaced by Lime route 8 between Washington & Sunderland with an identical route as it is now and also replaced by service X1 between Washington & Newcastle.
By the sounds of it, the 8 did directly replace the X2 between Sunderland & Washington.
RE: Go North East: Latest News & Discussion - February 2016
Ooo Friend, Bus Friend.