Automotive Plastics: headlamp housing, headlamp housing, unit

Question
Two curiosties, what type of plastic makes up the "back half" or housing side of the assembly? When a housing is damaged but repairable what material would work well? The lamp is from Honda CRV and the back half is black plastic. Also have a Toyota Camry that the back half is a light gray plastic.
Thanks for you time and consideration, Steve W.

Answer
Hi Steve, headlamp manufacturers use >PP< polypropylene plus a reinforcing load >PP+T20< for instance, the T20 stands for talcum in a 20% proportion. It does not matter whether black or grey, material is the same.

if you find a marking other than but similar to this let me know for further assistance.
Using the same material is the best option. so, I would use material from discarded units bearing the same code.

There are no adhesives or glues of any use for this application, just heat welding will do a strong union, filling or reinforcing.
thanks for your question.