Around 1971 or 1972, VW started using a washer under the large pinion bearing retainer nut in Type 1 and Type 2 transaxles. This required a slight change to the design of the main case (to accommodate the 2mm thick washer). If you are not sure which type of case you have, you can use calipers to measure the thickness of the case at the pinion bearing bore. If the thickness is approximately 22.2mm (.875") a washer is required. If it is approximately 24.2mm (.950") a washer should not be used.