I'm using a 65 temperature sending unit on my 67 because my intake does not have a port large enough to use the 67s sending unit. My question is, are all the sending units calibrated to work on one another's temperature gauges? I ask because while the 65 does work my temperature gauge seems to be reading higher than normal. From the short time I've driven it since I've put it in the gauge has been reading about 2/3-3/4 to H when the car has reached operating temperature. When I was driving it tonight it reached all the way to H but when I parked it there were no signs of an overheating car. No blown hoses, leaks, or boiling coolant. I have no clue what the actual temperature of the coolant is. I'm also using a hotter than stock thermostat.