Instrument unit - how many 1.5V & 3.0V bulbs total?
 

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I had my Cruise control light bulb missing. Noticed the code on durametric. When I looked at the rear of the panel I noticed there were many slots empty. Apparently some are not needed. So, instead of trying figure out I bought a dozen of each type and plugged them in. Now there are no empty ones and I know exactly which actually light up. And the rest are spares....