On the rear of the sliding door hinge there is 2 locking levers that hold the door in the open position.
This spring allows the locking levers to release from the catch plate allowing you to close the sliding door. This spring will fit either side sliding door on VW T2 Bays built from 1967 to 1979.
Sliding door hinge return spring for VW T2 Bay from 1967-1979.