I have never owned a Winnebago, but from what I see and learn when checking out these RV's and especially when talking to owners, Winnebago is a better Quality than FR Georgetown. However, a similar sized Winnebago is built on the same Ford Chassis as the Georgetown!
From what you are telling us, the noise at your RV is coming from the Chassis. Is it in sync with the RPM's of the engine, the wheels, the road joints? Is it still there when you slightly brake?
Could it be that a bolt fastening the superstructure to the chassis is lose and whenever you drive over a road joint it makes that noise or when the chassis for whatever reason gets twisted? There could be many reasons and a reputable mechanic should at least be able to narrow it down. Good luck and happy camping, Andy
Andy & Lisa
fulltiming in a
2006 Georgetown XL 359TS pulling a 2014 Chevy Sonic