Van was a '91 Carat Vanagon with 166k miles on the original heads.  Dealer
serviced for 145k miles until I bought it.  Coolant used to be green but was
kinda brown looking by the time it came out of the motor (looking to put a
rebuild in soon so I didn't bother to flush).
Head gasket blew catastrophically on the passenger side leaking coolant all
over the road.  Both heads were severely pitted and the gaskets were in
shreds on both sides (even the one that didn't blow).  Case was pitted as
well.  Both heads were cracked up into the water jacket even though the van
didn't overheat (according to the gauge anyway).  New heads, gaskets, and
alot of work later we are humming down the road again.  :)
More than you wanted to know?

Ken Wilford
http://www.vanagain.com
John 3:16
Phone: (856)-765-1583
Shop:   (856)-327-0027
Fax:     (856)-327-2242