I put a 180 degree thermostat in my D1 and it actually runs at about 180 degrees consistently. The gauge on the dash won't even move until you get well past 200 so good to monitor it with something else. Mine rarely ever goes past 200...Silly me to believe the 180 degF/ 82 degC labeling - just wondering if anybody else had noticed this "discrepancy" is all. My jeep w/4.0l cast iron block & head seems to run comfortably at 195 degF (what the t-stat is labeled as) and everybody says not to run it colder.