Does anyone know whether a cabled speedometer can be fitted on a '89 240DL with an electronic speedo? I know there's no problem at the dashboard end but I can't tell whether the transmission still has the right fitting (no hoist & plenty of snow...).

Alternatively: would an exagerated speed readout and no action on the odometer point to the sensor, the instrument or bad contacts? I already checked that the odometer internal mechanism is free to turn, contacts at instrument seem OK.

Thanks.