Agree with George's checklist above. If you can find a Cummins CoachCare certified shop in your area, they should be able to do all of that except the tires. Most any commercial truck tire shop can replace your tires.
I'd also replace my serpentine belt on the engine just for good measure. We just got our 6 year old Allure and I did all the stuff on George's list along with new serpentine belt and had the differential lube changed.
2019 Grand Design Solitude 384GK 5th wheel. Glen Allen, VA