Best I can come up with was a repair to my '79 rabbit.  We were in
Ellensburg, WA, looking for college apartments.  100 or so miles from home.
I noticed water leaking out by the fan switch, went to tighten it a bit and
the whole assembly came off in my hands.  The plastic collar had broken
cleanly off.  My buddy Jeff and I went to the local supermarket, where he
bought a rubber dog toy - shaped like a dumbbell - with an octagonal
cross-section a little bigger than the hole in the radiator.  He then used
my pocket knife to cut threads in it and screwed it into the hole.  We
re-filled the radiator, scavenged my fog light wiring to make a switch for
the fan and drove successfully home over the cascade mountains.

Randy, Carla & Anna Huyck, Olympia, WA
'75 Rustfalia
'85 Vanagon GL
'74 Super Beetle
'01 Ford F150