Not sure if this will ever be useful to anyone else, but I figure I'll put it out there just in case. Here is a list of differences that I documented while working on my gauge cluster project. If you've got any more details of the variations in gauge clusters throughout the years (or perhaps from different markets), please post them here.
List of noteworthy differences between 93 and 97 gauge clusters:
- 97 is prewired for vehicles with ABS and automatic transmissions--This includes a hold/overdrive lamp, ABS lamp, and low washer fluid lamp. 93 has the spaces for these lamps, but there is no overdrive cutout on the gauge face and the circuitry for all three lamps is incomplete. I think that in earlier years the clusters were only wired with the functions that their respect package included, while later years were wired to be compatible with all options.
- The "overdrive" lamp circuit in the 93 cluster appears to include a dimmer function, while the "hold" lamp circuit in the 97 does not.
- There is a 180-ohm 2W resistor for the fuel level gauge that jumpers a trace on the circuit board of the cluster in most years. It appears to be absent in many (if not all) of the 97 clusters. This resistor helps calibrate the fuel level gauge so that in earlier years it moves from F to E with the tank. In later years (which are missing the resistor), the needle goes past F and E. On a full tank, it floats above F until approximately 10-11 gallons and then begins to move. E represents approximately 2 gallons.
- Tachometer gauge face on 93 car shows partial red beginning at 6.5K rpm and full red at 7K whereas 97 only shows full red at 7K.
- Completely different oil pressure gauges. They are physically interchangeable, but the sender would need to be swapped as well.
- Completely different water temperature gauges. They are NOT physically interchangeable as the mounting bolts are located differently and the circuit is printed differently on the back of each cluster. They do however both use the same sending unit, so while you cannot switch the gauge between clusters, you can switch entire clusters and retain a functioning water temp gauge.
- UNCONFIRMED RUMOR: The speedometer/odometer is geared differently due to the earlier cars using a shorter final drive ratio. The speedometer seems to indicate a bit higher than the unit in my '97 cluster, but I think this is a natural variance between units and not necessarily an indication that the 1.6L clusters were geared differently. Both gauges were marked with "60 MPH = 1024 RPM" on the back, so I assume that they are meant to be calibrated the same. When the '93 unit indicates 60mph, the car is actually traveling 57mph. This is exactly the same as the '97 unit. However, at speeds above 60mph, the '97 unit appears to have less deviance from real speed than the '93 unit has.
- The earlier models had metal trim rings/bezels around the speedometer and tachometer, which are missing from the gauge clusters on later models.