The air suspension module only needs a speed reference via the K-line. It is also connected to the CAN bus so it can talk with the ABS/ESP
"The driving speed signal ... ... is a square-wave signal produced by the dash panel, the frequency of which is changed in accordance with the vehicle speed. ... is required in the evaluation of the driving condition (stationary/driving mode) and thereby for selection of the control criteria (see “Control concept”). The interface for the driving speed signal is redundant, as the information regarding speed is also transmitted by the CAN bus. K wire Communication for self-diagnosis between control unit J197 and the diagnostic tester takes place via the familiar K wire by means of conventional data messages. The self-diagnosis K wire must not be confused with the K wire connecting operating unit E281 to control unit J197." [SSP 243]
But you would need a diesel cluster for the glow plug indicator - the EDC16 ECU is not happy with a gasser cluster.