B9TLs have 5 now 
best is i took 9680d on 80 the upper deck lights were all
disfunctional and in svc.
Rear lights as in the red ones, like 9889.
Mechanically in general, the tridents are in terrible shape as
well, considering their relative age. Engines rough, gearbox
doesn't seem responsive, particularly downwards. And I don't
understand. The 3rd gear is tuned "tight", it is actually possible
for a trident to stay at 2nd on the expressway and that probably
stresses the engine as well. Worst would of course be the
aircon+suspension effect, headache inducing.
Overall, the tridents don't quite offer a ride you would like
after a hard day's work.