Even after getting tire pressures sorted out, and pressures for air springs if you have them, the ride in a C is going to be rough on the small, sharp bumps like expansion joints and potholes.
To control the associated noise, you need to figure out what is banging, and manage that. Dishes, pots, pans may need a little bit of padding between. Rubber non-skid mats on shelves will help. Two noisiest things in my C were the turntable for the micrwave and the rack in the oven; these now have a different storage place for travel.
Mostly it is about tracking things down one by one, not easy at the beginning because so many things are banging around. Motorhome as old as yours, even some doors and drawers could be loose or have loose supports. You get as much banging around in a travel trailer, but you are not there to hear it while moving.
