Answer:
To change the thermostat--
* drain the cooling system down to thermostat level (or lower)
* remove the two (2) thermostat housing bolts, and the housing itself
* remove old thermostat, discard gasket and clean both gasket sealing surfaces (pay attention to the orientation of the thermostat when you took it out; it only works one way)
* install the new thermostat
* place new gasket onto water box surface, over the thermostat, and center the thermostat in the opening of the intake manifold
* apply gasket sealant, if necessary
* place the housing over the gasket and thermostat, and torque bolts down to 250 in. lbs.
* refill cooling system to compensate for lost coolant