IMHO, for most mass produced RV's, after an RV reaches about 5 years of age, an owner will have little or no contact with the factory.
The chassis/engine would be supported by that brand's shops and the "house" is a collection of third party built systems for most everything from the jacks to the water pump shared by many brands. Owner maint or any good RV shop can address most all of that
Having said that, Gulf Stream made a good motorhome. They stayed in buisness through and after the 2008 recession when other brands closed their doors, by cutting back to their core products (towables), so the company is still there to request diagrams and such.
There is a Gulf Stream owner's Forum on iRV2, if there are any specific questions:
Gulf Stream Owner's Forum - iRV2 Forums
I submit that for a used RV, any TLC over the years that have passed is a much more important factor to a rig's value over any perceived brand reputation.
Kim and Steve, Mustang LCDR (Ret), '07 Damon Outlaw #1193
I have seen gross intolerance shown in support of tolerance, Samuel Coleridge
WE LOVE OUR OUTLAW RV