I was just talking with my dealer on this subject. The Geny prep includes the insulated housing, the wiring and the fuel tank. It would be very costly at the dealer rate of $120+ per hour to install the Geny prep after delivery. You also have to install the exhaust piping when the Geny is installed. Best to order the Geny from the factory if you expect to have a need for one.
Prospective RV Buyer
RAM Laramie Longhorn 3500 SRW 6.7 L Cummins Diesel