Components to rvs like tires, a/c, fridge, furnace, awning are warranteed by their mfgr. Its clear in your service and warranty package.
Grand Design will help you with an issue related to failure of the component. The rv assembler ( builder) only assumes responsibility for their build and installation of outside supplied components.
We see this many times a year in our camp , with rv problems. The mfgr.( final assembler) of an rv uses many outside suppliers for components, much like a sticks & bricks. They are warranted by their maker.
A home builder is not responsible for a warranty issue with the water heater or fridge, for example.
Hope this helps. Max