Call any of the major truck dealers like Kenworth, Peterbuilt, Mack, International, etc. I'd make an appointment and I'd take your own oil and fuel filters as they could have a hard time getting them with all of the parts shortages.
When was the last time you had the air dryer serviced on your air brakes?
Service the generator also while you're there?
Bill
Nodwell RN110 out moose hunting. 4-53 Detroit, Clark 5 spd, 40" wide tracks, 10:00x20 tires, 16,000# capacity, 22,000# weight. You know the mud is getting deep when it's coming in the doors.