In my 65 Belvedere, I have an aftermarket Bosch temp gauge. The sending unit was acting up, sometimes working, not working blah blah blah. Well the threaded stem seemed loose and was moving when I tried to unscrew the nut. And the nut seemed to be somewhat stripped. I had a stock sending unit laying around but it's about a 1/4 inch shorter. I installed it and took the car for a drive. The temp gauge was way up around 240. The engine ran great and showed no signs of getting hot. Are the sending units calibrated differently? If so I guess I'll have to order a Bosch unit.