If your standing at the front of the car facing the engine. The thermostat is located down where the head meets the block on the top left corner. A ground does come off that one, but it goes back into the the wiring harness. The main ground I would worry about is the one coming off the battery, the one coming off the starter motor(Acts as -tve for it too work) One off the Gearbox and 2 off of the valve cover.
