LS Engine Swap M12 1.5 Adapter to 3/8 NPT Coolant Temperature Sensor Water LS1 LSX LS3, 179 Coolant Temperature Male M12-1.5 to Female 3/8" NPT This adapts SBC and BBC 3/8" NPT coolant temperature sensors to fit LS cylinder heads. Will fit sensors with up to .85" length, measured from probe tip to the outer edge of adapter. Most aftermarket gauges will use a 3/8" NPT thread adapter (usually included with gauge)