According to Bus Lists on the Web
Early e400s were listed as Tridents
WA56FUD | AD Tt SFD45MBRA6GX34108 | AD 6411/1 | H39/32F | 12/2006 | First Devon & Cornwall | 33412 |
So these Optare bodied vehicles are also listed as Tridents
LX58CWO | AD Tt SFD16MBRA8GXE4907 | Oe C71002 | H43/21D | 12/2008 | London General | DOE2 |
E400s continued to be listed as Tridents
SN59AVU | AD Tt SFD18SBRF9GXB5340 | AD 9412/3 | H41/26D | 11/2009 | Travel London | 9507 |
However, the subsequently, they became e40D during 2011
SN61DFE | AD E40D SFD1DSBRFBGXB6263 | AD B426/21 | H41/24D | 11/2011 | London Central | E225 |
Someone like
@Jordan Adam may know but was the chassis reworked for Euro V and that meant the Trident ceased to exist c.2011