They have to be somewhere in the heater hoses running from the front of the engine down to the metal heater pipes welded into the floor. I've seen them hose-clamped to the steel upper radiator pipe from engine to surge tank, and bolted to the inner rocker panel on the rt side. Both are quickly reachable from outside the car if you know where. Try positioning them so that road debris won't turn the levers ON or OFF. Some guys 'gang' the levers so they can be turned with a Bowden cable or a knob on a steel rod from the drivers seat.