Reference Details
- Common issue
- winged sump, 780 Holley, rear discs, choke control, or Globe wheels used to relabel an RPO 83 as Phase IV
- Confidence
- documented
- Correct value
- Phase IV identity requires one of the four documented program-car histories; RPO 83 is a later related XA GT option path
- Where to check
- factory plate, build record, Ford Special Vehicles documentation, and vehicle chronology