yo,
To route the wiring, I used the clutch blank (assuming you have the E4OD) and bought a proper sized grommet at NAPA,
here it is coutesy of Ken
http://www.froggmann.com/Images/BMinst.jpg
or under glove box; look for a grommet or drill there.
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92vabronco mtd the tach in front of the cluster and added gauges to dash, center:
Coolant Temp, Oil Pressure, Oil Temp, & Trans Temp
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How about an A Pillar Mount such as this by bearfoot_25?
I have some dash mtd pics, but they the tach is right in the cross eyed vision sight
Others have mtd'es tachs on steering column, but that sinks too due ro tranny & MFS stalks, and cluster vision interference.
GL!