Just thought I might save someone from an uncomfortable crawl under the dash:



Stock temp gauge suddenly moved up to "H" while driving on the highway. First thought was; another thermostat failure! But, before I could panic, needle dropped back to normal. Symptom recurred intermittently, but predictably, and gauge moved too quickly to be a real indication of actual engine temp. So, I replaced the OEM 6V sending unit (NOS) first since my gauge was fairly new, and draining a little coolant seemed easier than the contortionist routine. PROBLEM SOLVED!

6 VOLTS/POS. GRD. NW INDIANA