Coolant Flushing, IMHO....

0) get the engine warm enough to open the thermostat, turn heater valves all
full on.

1) take off lower grill and with a pair of vice grips open the spring clip
on the lower rad hose (pass. side), wiggle it down and off,  and dump the
old coolant into a bucket, then ditch properly.  Slip the hose back on
without clamp.  To really dump all the coolant from the block you need to
remove 2 Allen head bolts drom underneath the cylinders between the pushrod
tubes, which are covered by the gravel shields. PITA! 

2) Stuff a garden hose in the main reservoir in back and fill it up, then
start the engine and keep filling.  Let the engine get warmed up again and
moving coolant in entire system, then shut off and do 1) again.

3) Refill again, and add some rad flush chem (i used a liquid Prestone, not
the powder highly caustic one) and run it well up to temp, 15-20 minutes.
Easiest way is to put the hose clamp back on and go for a drive.

4) Dump out the gray and greasy water/flush in disgust, then repeat 1) and
2) until the water is coming out clear.  May take 3 or 4 tries as you are
not properly draining the engine block each time, just the rad and hoses.

5)There will be about a gallon of coolant left in the system each rinse, so
when it comes time to add fresh coolant mix up 1/2 gallon and add that.
After connecting everything back up run the engine to get a good mixing and
add straight antifreeze and run for a few minutes then check coolant
strength.  Just adding premixed 70/30 ratio will result in a very weak mix
that will freeze.  Always verify the strength.  Needless to say, have fun
bleeding the airbubbles out as you refill!!

Tim