Rear lights on railcars

I have just rewired (again) my Billard A80. I have decided that for simplicity, all the lights will work off the same output from the decoder, so the rear headlight is on as well as the front one and the inside lights, regardless of which direction it is going in. (Looks nicer in the dark.) Of course it is possible to have all three operating separately, but this would only be worth it if there was a separate rear light (red?). Single ended cars (e.g the early De Dions) did have a rear light (note to Mikey - even M Tartary's lashups had them) I have looked at lots of photos of Billards and have yet to spot a rear light. They all seem to have either one or two headlights at each end. So the question is: did French local railways' Billard (or other bi-directional) railcars display a rear red light? And if so, where was it?

Phil

Billard 80s did have a rear red light Phil.
Generally this was just a single very small inset lamp above the central window on the motored and non motored end.
I have also seen 2 on the motored end , 1 either side of the radiator grill below the windows, again very small and inset.

There were many varariations and mods though.

I will try and find some pictures.
Try this link to one of Maarten Meuwes pics of a Vivarais machine.
Billard 80

However later French railcar practice was to have red disc(s) which slotted over headlight(s).

Thanks Carl: that looks doable. I really had not spotted that tiny light before , but once pointed out it is obvious! I've got some red bulbs in stock..but maybe I'll leave to later in the year.