Good day fleshly.! Welcome.
I would start by looking for used parts on eBay, auto recyclers ( car-parts.com) and posting in the wanted sections of the forums on the internet. I am not sure where you live but pm me a message if you can not find what you need. (I likely have what you need)
Have you tried your gm dealer? Or gmpartsonline.com
Good luck and hope you find what you need to get you going. Please post your progress here.