You didn't say if this is a class A or a class C motorhome. The class C's used a wider rear than the class A chassis did just as a dually P/U has a wider axle than a "one-ton" cab and chassis uses. Be careful that yours is correct for whatever it is you intend to do. As for the frame it is likely a Parrish or some other outside vendor that GM used and supplied to Holiday Rambler as a motorized chassis but is rated as GVWR and by GAWR and will satisfy those requirements.
