Actually it was pretty easy. Good soldering along with a low mass iron such as a Metcal is in order along with 1.5K ohm resistors. Just get some good high brightness LEDs that match the color of the backlit labels and form up the leads to get 1/8" of leg to solder one side down to the foil and cut and form the resistor to fit in line to make the other leg, polarity of the resistor is not important however the LEDs are polarity sensitive... Backwards results in no light. You can use heat shrink to cover one lead if you like but makes no difference really, just adds mass to vibrate. You will need to get an electrical diagram that shows the connection points or you can use your trusty meter to measure. Note Oil, Parking Brake and Brake warn all go LOW to illuminate and the others will go HIGH meaning they are grounded with the low going signals needing a ground to light.
You also might want to stack 4 LEDs in some of the darker places such as the OD indicator. Each position should have 2 LEDs to be effective but I went 4 per hole using T-1 size clear LEDs with 10 degree beam spreads.

Instrument backlighting are high brightness white LEDs wired 4 per leg in series and connected directly to the +12v power source for lighting. You will have to run the cluster on the bench and carefully aim the backlight LEDs to evenly cover the inside of the gauges, direct them through the plastic light guides already in place. Use T-1 size 4000 Mcd white LEDs from Digi-Key (.com) or other supplier, don't buy any of the cheapie LEDs you see at discount prices as they are inconsistant instead get them in a batch from Digi-Key as they are lot matched and made by Panasonic I believe. The dimmer will function as normal however as white LEDs dim they become very blue in color and fall off fast.

Total current draw with all the lights going will be under 500 Ma and no real increase in temprature.

Pretty simple eh?

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