Besides owning pickups and 4Runners, I bought a '96 Land Cruiser. The cruisers seem to have their own fair share of head gasket issues, and a strange coolant sludging problem in which grayish tan silt builds up in the overflow reservoir. The link below goes to a very good land cruiser forum, but more importantly, shows a really nice coolant filter setup.

http://forum.ih8mud.com/showthread.php?t=96963&highlight=coolant+filter