Winnebago put that on a Freightliner chassis. Freightliner service centers will take care of the chassis, whether it is powered by Cat, Cummins, Detroit, or Mercedes-Benz. They usually also are service centers for Cummins-Onan power equipment.
What you get is factory service. Factory service is not cheap, but it is usually competent.
There are smaller, independent truck service businesses that might charge less for services (parts will be about the same). Many are very good, but you need to know who you are dealing with.
For house stuff (other than the generator) you are at the mercy of RV service shops.
Smaller C motorhomes are in the same situation. For me it is Ford dealer, a local alignment/tire/brake shop for the chassis, local RV dealer for house stuff, and I have to find an authorized Cummins/Onan service center to take care of the generator.