Dumb Question - how to flush cooling system on M1008...?

This may sound like a stupid Newbie Question, but I have searched on this topic with no results.

Question :

How do you “flush” a radiator, and water cooling system, and cab heater core on a M1008 CUCV. ?

I get no heat from my heater ( The fan works OK)....and suspect the coling system may be full of crap. How do I tell if that is the problem, or if it is due to a malfunctioning thermostat ?

well if its just the heater core you want to fluch i will tell you how i do mine,
disconnect both sides of the heater core and cut the end of a garden hose off* the male end not the female end* and hook it to the inlet side of the heater core and turn the hose on. if theres a blockage it should flush it out. keep in mind your milage may vary and if you rupture your core its not my fault lol