I used a 1/2 inch plastic elbow pipe which is used with the black flexible
plastic pipe.  The elbow is barbed on both ends.  Just slip the hoses on and
clamp.  You're back on the road.  By the way, a Rabbit heater core will work
as a Vanagon rear heater core.  Requires some modification to the fan housing
 with a jig saw but is cheap and the Rabbit cores are built better.  When you
go to the junkyard, take your heater core with you so you can be sure that
the inlet and outlet pipes are pointed in the right direction.

Tom
'71, '77 and '85 Westys