9. With the bulk of the fuel stuff complete, we turned our attention to the temp sensor. Since the Chevelle already has two temp sensors feeding gauges and fans, finding a spot for the MSD had us breaking out the drill. Our Chevelle has a cast iron thermostat housing from an ’80s-era Monte Carlo that has a flat area cast into it. We drilled and tapped the thermostat housing in that location with a 37/64-inch drill bit and a 3/8-inch NPT tap.