The X-3, as currently in the National Museum of the US Air Force, has two oil pressure gauges per engine, and one fuel pressure gauge per engine. One of the per-engine oil pressure gauges is labeled as being for the turbojet, the other for the afterburner. (But why would an afterburner need lubrication?)
The preliminary flight operating manual says that the engine instrumentation would be the other way around: one fuel pressure gauge for the turbojet part and one for the afterburner part of each engine, and just one oil pressure gauge per engine. What could it be that the two separate oil pressure gauges per engine measure?