The base of the windshield on all 126's are heated by coolant.
There is a thin plastic bladder under the area the wiper blades rest on. The hoses that connect to the bladder come off of the watervalve for the heater. As far as I know all 126's are this way.
There is only 1 repair kit needed, it isn't a dual valve. Dual valves were used starting with the 129 and 140 chassis which have dual zone (right/left) heating.

Gilly