Reproduction 1974-1979 Bus Sliding Side Door Stop Buffer for correct operations of you interior light switch.
This rubber stop or buffer allows the interior lighting to be turned on and off when the sliding door is opened and closed. If this rubber is missing, the interior light will not be turned off when the sliding door is closed. If the rubber is worn, the interior light may come on regularly while driving. Replace the rubber stop and your interior light will work again as it should.