The serial numbers you have given us on the various pictures are a mixture of different gauges bought at several different times. The final picture you sent shows a mixture of parts.
This picture shows two 48” antennas, four sensor electronics, two Operator Interfaces and several interconnecting cables.
A standard gauge requires:
Operator Interface.
An interconnecting cable
An sensor electronics box
A 48” antenna complete with coax cables.
As these gauges were supplied at different times there will be differences in the firmware installed in each sensor electronics and the Operator Interfaces. To make a working gauge you need to use items that have the same serial number.
In the pictures there is an Operator Interface 91-0026P, a sensor electronics 91-0026S, an antenna with coax cables and an interconnecting cable.
Use these parts to try to make a complete gauge.
The antenna has two coax cables on is connected to the center rail of the antenna and is marked MEAS at the end that connects to the sensor electronics. The other is not connected to anything at the antenna and it is a Reference cable, marked REF at the electronics end.
The sensor electronics box has two coax sockets that should be labelled MEAS and REF. Connect the cables to the respective sockets. If the sensor electronics boxes are missing the labels then remove the cover and you will see the sockets connect to the oscillator board Meas goes to Live on the board and Ref goes to Ref on the board.
Connect the grey cable from the sensor electronic to the OI and apply power.
If the firmware boots up you need to go Engineering and find the line for Resetting the firmware to factory defaults. Do that.
Then go to Diagnostics and see what the measure and reference counts read. They should be in the be close to each other. The tuning voltage should be 3.5V approx. If all is fine then the phenolic should be set to read 50 in the Cal Set up. That is how they leave the factory.
With all these assorted parts it really would be best for everything to come back to PSC and we can repair/upgrade/ etc to make a number of complete gauges.