Does anyone know the difference between the factory OEM "severe duty" thermostat (180*) vs. the standard OEM t-stat (195*). I went to the stealership to get a new factory t-stat and I had both of these to chose from for my '96 4.0L. Those of you who've been sucked in the heating problem threads know that a lot of people recommend the 195* OEM standard t-stat because it comes with the little ventilation nipple/hole that's not in after market thermostats. They're special order parts and I'm inclined to buy the "severe duty" but would like some advice. Yes, my XJ runs hot and overheats and I'm trying to restore all cooling back to stock, so I can troubleshoot it properly.