This is the fastener for the plastic lock plate that locks the transmission sidescrew adjusting ring. Fits all manual transmission Vanagons including Syncro. Two per cap, four per van.  Sold...

This side screw adjuster is how you adjust the pinion depth and backlash in your VW transmission.  This is an essential procedure when rebuilding your transmission or installing a limited slip...

This washer/plate spreads the clamping force on the plastic cap located on the transmission behind the drive flanges.  The plastic cap locks the side screw adjusting ring into place. Fits all...

When you find transmission oil inside your inner CV boot (as opposed to just CV grease), this will be the culprit. The part received may be a different color than pictured here. Fits all 1980-1991...