Yes it will be a Ford cap. The Ford chassis, dashboard, brakes, wheels, front clip, steering, drive train and gas tank, filler neck and gas cap come from the Ford factory. All the rest is retrofitted when the RV shell is bolted to the manufactured floor. No special to one gas cap is used. Jayco may build the filler door but the cap and filler neck are all FoMoCo parts.
2016 Chevy LTZ - Duramax/Allison
2008 Eagle 30.5BHS