If they're 9 years old, you got your life out of them and then some.
Even though the other two may be okay, all four need to be replaced. It's noy a good idea to mate old with new. They'll be unbalanced.
This is also a good chance to go AGM if you currently have lead acid. With AGM there is no maintenance like you have with lead acid.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor