OK the short version, I have a running driving 27ft RV. It's a P chassis 454 and TBI. The body is delaminating bad and don't need it anyway. The thought is put some common cheap cab on it and build an awesome flat bed dump bed. Now it's a car hauler or whatever hauler. Anyone familiar enough with the P chassis and what cabs might be the list work. 1/2 tempted just to set a square cab on it. And no crazy stuff like find an old COE cab just looking, for easy to find and most functional. Do Dodge or Ford Box van cabs in bolt from the frame? I'm thinking GM/Ford/Dodge C class motor home or box truck cab.
I think Fords are a unibody type. I had an older one and it didn't have an actual frame like a P chasis has.
Richard, we need a picture. Where is the driver location in relationship to the engine and front axle? If it is a short nose, I like @Catbox 's idea.
Ford Econoline cutaway used for class C motor home or box van is definitely full frame with separate cab from '75 until now. The full van stopped production in 2015 and Econoline is only sold as cutaway for RV/box van. The new Transit van is a unibody but is available as a cutaway with stamped type frame rails out back instead of c channel full frame.