Hi Norman,
Sorry I cant help source the lights.
The old Leyland, AEC and most others had all black cabling with labels attatched, needless to say the labels soon disappeared leaving us with a similar problem to yours.
Part of my tool kit in those days was a battery operated electric door bell, ( I don't know if you can buy such a thing anymore). Attatch a small crocodile clip to one bell lead and a probe to the other, connect the clip to the cable you want to trace and probe around for the other end of the cable with the other lead till the bell rings. Simple.
Even now I've been tracing some wires in my sons bus and find that quicker and easier than using a multimeter. Some of the old ways are still the best.
![Laughing :lol:](./images/smilies/icon_lol.gif)