where is the thermostat in the z28 camaro

Follow your upper radiator hose to the intake manifold. The housing is there, should be two bolt. It's underneath that housing.

  Is it the Thermo-Sensor, or the "round, mechanical" one? If it's the Thermostat that turns on your fans, it should be on top the the manifold, next to the temp-sensor. Though I'm on my 4th Z28 and seen every them in the block, on the water-neck housing ect. Buy a Haynes or Chilton, it will save alot of time, money and bloody knuckles...
~scott