All SG-plated and BSEP Registered Buses (Tower Transit, Go-Ahead) have new DDU.
In addition, all Svcs 21, 52, 157, 163 have new DDU as of October 7, 2016.
A lot KJDEP buses except enviros recently transferred from WPDEP and more...
SMB293G with DDU, spotted on 172 today
No wonder I didn't see this bus on 307 for quite a while until now. OCs on 307 should be replacing those buses installing DDU