My new rear heater core was a pleasure to install.  Surely as you said, it
was indeed leaking.  When I pulled it out you could a small puddle of
coolant in the plastic blower box.  Thanks for the advice on clamping the
two heater hoses with wood blocks.   It works.  Also, the poster who
advised to fill up the new core before finishing the install.  That was
good.  Prevented me from having to bleed the system once more.  I did not
replace the heater valve because it was not leaking.

The new core had VW emblems which had been ground off by the aftermarkt
distributor.  Interesting, it obviously originated in VW land.  Also, the
original core has a nice little white plastic bleed screw with very fine
machine threads.  The new core had this hole sealed with plastic.  No cap.
When I first saw it there was what appeared to be a hole.  I thought I
would have the get my old cap and insert, but surprise, no hole.

What about the gasket?  Where the new core mates to the heater valve, it
appeared a gasket was needed.  But none was on the old install, so I
slapped 'em together and tightened sufficiently.  Did not consult any
torque values, and I don't have a torque wrench anyway.  I keep that stuff
in my noodle, as Mozart says.  Head bolts, that's a horse of a different
color.

Cleaned the box and vents with Simple Green and decontaminated everything.
 Not a drop of leak when operated.

Mission accomplished!  <applause>

The old core is cool.  Looks like an evaporator.  The fins are tiny and
very close togetber.  It is practically like new.  I really hate to throw
it out because I just know one of you is dedicated enough to know exactly
how to fix it.  Or if you just want to experiment with it, or whatever.
Anyone who wants it can have it for the shipping cost.  Maybe this sounds
stupid, but I would like to know if they can be fixed.

HK Sawyer
Georgia
91 West Fail-No-More