what type of undercoating used on w123 lower front fenders/air damn?
 

I'm painting the lower front portion of the fenders - there is some kind of textured protective coating on the body color on that part of the car originally. Does anybody know what available spray can product is similar to the factory coating in this area? I think the inner lips of the fenders are coated with same thing - underneath the body color layer.

Doesn't seem to be like the rubberized undercoating (much harder) but not sure if its like the stone/chip guard either.

It is called Chip Guard. To spray it, you will need a gun with a pressurized pot. I've written a lot on the stuff. you should be able to find info on the site.