740 speedometer/mileometer connections

Getrie has a very erratic mileometer, sometimes it goes, sometimes it doesn't. The speedometer is fine, which to me eliminates the axle sender and the undercar wiring etc. I suspect that its actually a mechanical problem with the mileometer./ I bought off e-bay a coplete new instrument panel for a 740, but it won't fit! All the wiring plugs etc are the same, apart from the connection to the back of the speedo. Mine has THREE connectors on the plug, the panel I got has FOUR. Anyone know what the differences are, where IO can get the right panel, and/or, is the mileometer up for taking apart and overhauling (Question for Foggy, 1st Raven, J-o-6 etc etc??)

there are two different make instrument panels , VDO and Yazaki nothing is interchangable on them of course .. Yazaki has the trip counter digits in separate windows . The VDO has three trip meter digits in one wide window and the tenths digit in it's own window , Thats how you tell them apart ..

I got a Yakazi voltmeter to work on a VDO panel once :)