If your Syncro came with a front differentail from the factory then your van uses this plunger. It makes you pull out and rotate the knob to lock the front differential. Just in case yours has broken...

Syncro front axle nut for 1986-91 Syncro Vanagons. Two per van, sold individually. Ref ID: N10085301 Shop by Diagram Hover over the icon and click to get the detail.  

Wiper arm nut cover/wiper cap. 2 in the front and 1 in the rear. Sold individually. Two different angles are pictured. Ref ID: 133955435

This stainless steel locking diff actuator bracket works for both rear and front locking differentials in the VW T3 Syncro.  It is equipped with mounting provisions that make it compatible with...

This o-ring pulls double duty in your 1986-91 Syncro vanagon. Fits: Speedometer drive sleeve in the front differential Aluminum sleeve on the diff lock actuator shaft Two per Syncro, sold...