should the backside of the front and rear valances on a 71 cuda be body colour or dip primer or?? thanks! also,valances on or off before shooting factory undercoating?

99% sure valances are not body color on the backside.

Not sure about the undercoating timing

I remember there was a big discussion about this when Dave Walden was restoring his Challenger. I don't remember all the specifics and I'm not sure if that info was saved in the archives or not. I seem to remember him saying that the rear valance was installed "before" the car was painted body color. The front valance was not installed but was hanging in front of the car or in the windshield opening while the body was painted. Both should have some body color overspray on the back side.(probably more on the front then the rear) I also seem to remember him saying that the front valance was installed "after" the radiator blackout since there was black paint in areas "behind" the front valance. Not sure about undercoating though.

I know Challengers had the back side of the front valance blacked out.(in the center) Not sure about if Cudas were the same way.

i will try to dig up a picture of my LA built Cuda during disassembly. Burdar is right, there was primer on the inside of the valence and appeared to have been painted off the car since there was little B7 overspray on it as well.

I can't say for sure, but I doubt that the rear valance was installed before paint.
It would mean that they would have to install it then take it back off to put the rear suspension (springs) in.
I can't see them wasting the man hours to do that having retired from a Chrysler Assembly plant.

It may have been painted at the same time, they did that with some parts suspended on brackets with the vehicle.
I know that's how they did it on the Ram trucks.