Sedan and wagons take different speedometer/odometer due to different size tires spec'd for the two bodies. Sedans take 10042, wagons take 9800. The "wrong" one will work but it will be inaccurate by about 2.5%.

Checking the illumination bulbs - these are the 1/4-turn bulbs near top of cluster, that are NOT located directly behind the green turn signal locations. '89 and later takes a halogen bulb that's about $9 ea from fcpgroton.com (you may have to call them to buy it). I try to harvest those from junkers when possible. '86 takes a different bulb, much less expensive and less bright. Not sure exactly when the change was made.

PLT had good notes on the wiring hookup. Copied + edited slightly below.

The Red/White wire is your Tach connection.
Yellow Red on the lower left hand side (viewing from back side of cluster).
There is not a jumper for cluster illumination except for the fusible link across the top of the cluster.
The two prong on the upper left side of the speedo (viewing from the back side of cluster) is for the Cruise Control and if you have one should be an orange wire. The two prongs are a single metal piece.

The three prong on the back of the tach is where the small clock plugs in.

You didn't mention the small clock - if you can, go back and get it! Replaces a blanking plate to the right of the cluster. The three wires are for constant power, dimmed power for illumination, and ground. If the clock doesn't work you can repair it if you can solder. Opening it without damage is the toughest part but it's doable.
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Sven: '89 245 NA, 951 ECU, expanded air dam, forward belly pan reaches oem belly pan, airbox heater upgraded, E-fan, 205/65-15 at 50 psi, IPD sways, no a/c-p/s belt, E-Codes, amber front corner reflectors, aero front face, quad horns, tach, small clock.