As others have said, the OBD2 port on the right side of the steering column, often up out of sight and hard to spot with the plastic cap on it. The Ford body builders manual calls for it being relocated to more accessible spot, but few coach manufacturers bother. The 460 V8 equipped 1997 F-53's were the last to have the OBD(1) port under the dog house. There were no 1998 F53's manufactured, but your 1998 coach might have been on a 1997 chassis. The quick way to be sure which you have is the engine. Through '97, F53's had the 460 V8. From '99 on they've had the Triton V10.
