BTW, once you have the plastic heater valve off, this gives you the access you need to insert your garden hose and black flush the crud out of the heater box, with the hoses removed for replacement. (SAVE theese for measuring the new hose, which must be cut to make two -- the inlet and return)

Also, without needing to hunt under the crowded turbo & manifold (if so equipped) I managed to flush the engine block from the same location because you can remove the heater hose at the block and force water through the block from the thermostat (once removed). The engine block connection to the heater hose becomes, in effect, the draincock.