Reglover,
There should be 2 serial numbers - one from Holiday Rambler (all numbers) and the other Ford's VIN (should have "F53" in it). Do you have the Ford chassis booklet? The 800 # for the Ford F-53 motor home chassis should be in the booklet. They should be able to help you. If you don't have the 800#, leave a message here on the board. It's cold and windy with snow flurries right now so I'm passing on going into the garage and find my booklet.