The control unit is a box 7.5"x3.5"x2" Bosch P/N 0 265 101 016 In the 126 chassis it is located in the "double firewall" area just forward of the cowl. I confess I am uncertain of the location in a 107; perhaps in the right kick panel, or above the right footspace, if it is not in the engine room. The wire bundle is about 1/2" in diameter; tracing from the accuator may help.

The Ebay listing was for a SEL/SEC; the rear end center piece is the same in the SL, and the sensors will interchange. The sensor is mounted in the diff. and the trigger wheel is on the pinion.