Instrument cluster fixes/upgrades?

You don't need a diagram, just follow the traces on the board. A diagram does not exist unless someone made one. The factory diagram shows what harness pins goes where from the harness side.

I did not think / realize you have a Ralleye dash. On those the IVR is built into the fuel gauge. If yours is working, great. If you have to replace it, you will have to disable the one internally and piggyback one to the outside.

If you can post a good clear shot (or two overlapping) of the rear and front of your cluster, we can tell you were things are and what they do.

You need a wiring diagram/ service manual for the car, if not dowload one free at MyMopar