Gauge Information

Notes on Speedometers
Most appear to use a 5 wire setup. Two wires receive power, two wires are power out to the next gauge in series, and the last goes to the speed sensor. Only difference may be mounting, wire length, and wire locations in the plugs. As far as I know, all read 0 to 60mph.
If a speedo has three wires, it still should work the same as the 5 wire, just doesn't have power out to the next gauge.

Notes on Tachometers
Most older models appear to use a 3 wire setup. Two wires receive power from the fuel or LCD gauge and the third (YL/RD) goes to the magneto. Only difference may be mounting, wire length, and wire locations in the plugs. As far as I know, all read 0 to 8000rpm.
Most newer models use a 5 wire setup and are in series with the fuel and/or tach and/or speedo. Two wires receive power, two wires are power out to the next gauge in series, and the last goes to the magneto (or MPEM). On gauges with the same number of wires but different part numbers, the only difference may be gauge face, wire length, and wire locations in the plugs.

Notes on LCD Gauge (1995/1996 2" model)
From what I see, they all use the same sensors (fuel/oil/temp) as the non-LCD 1990-1996 models. All 1995/1996 LCD equipped skis are interchangeable and the gauge should also work properly on earlier non-LCD years if desired.

Notes on LCD Gauge (1996 up 3.25" models)
From what I see, most all use the same sensors (fuel/oil/temp/compass/air temp/etc.). The GTX uses a LCD with the most functions, so it should be compatible with other models. The only thing you might need to do is leave some plugs disconnected/capped for missing sensors. Also note that different LCD part numbers may have the wires in different positions on the plugs, so that would have to be corrected for your model. Also, the RFI skis appear to need a RFI LCD Gauge. I believe it monitors the fuel injection.