Through testing I determined material is polyurethane, the same thing they make ATV body panels, motorcycle fenders and water tanks out of. I dealt with this place over the past few days:
http://www.urethanesupply.com/index.html and they were an amazing help. I have one of their airless welders on its way along with the welding rods for the polyurethane material. (there is no adhesive known to man that will bond polyurethane -you must weld it to repair it) Another problem is that it is very difficult to get paint to adhere to polyurethane. They even had a step by step on how to do that!
http://www.urethanesupply.com/atvpainting.html Great website. Now we know the reason these valances were molded in color: because there were no paints or additives to make the paint stick to them back then.