Most stock air cooled VW Bugs, Early Buses, Karmann Ghias, as well as Type 3's and Things use this type of spark plug. It is 14 mm 1/2 in. reac. Bosch stock # 7902
Note that if you have MOFOCO Performance heads then this is not the correct plug. MOFOCO heads need the 3/4in reach Bosch W8CC Plug