With an automatic transmission and A/C, your car should definitely have one. Maybe your engine was replaced at some point with a manual transmission engine? What is the engine number?
There is not much to the installation, you need the proper bracket and of course the wiring in place. The wiring ought to be there "somewhere". I have a spare one around, however it was not always able to move the linkages sufficiently so it is not 100%. These units are not easy to repair, although I came across some instructions how to. At a cost of Euro 290 it is worthwile to try.
Cees Klumper in Amsterdam
'69 white 280 SL automatic