We have sourced a crimp-on 1/4" quick disconnect terminal with strain relief and locking tab for 22-18 gage wire that is functionally equivalent to the quick disconnects used on the original Volkswagen wiring harness & fuse box.  These connectors have locking tabs to lock them into the fuse box and various connectors throughout the vehicle.  Don't use an ugly hardware store crimp terminal again!  They are a silver color rather than the original bronze color. These are sold in packs of 10.
 
We recommend a ratcheting-style crimping tool to install these connectors.