Try these guys. They are in York County. I think they brought a possum and other animals to my son's elementary school class. A snake, an owl, and maybe something else. I happened to be there that day. It was really cool. That was many years ago so I'm not sure what they are up to today

One thing that I learned about opossums that day is that they carry their newborns in a pouch for months. If you see a opossum that has been run over then it's possible to find babies on her even if she is not alive. The rescue place said they get a lot of those babies

https://www.thecenterforwildlife.org/

Good luck!