Faulty Temp Gauge???

[1st49Chevy]

i have a 59 chevy truck that i drive with no problems except when on the freeway the temp needle goes all the way to the right. i have changed out the temp sending unit with the correct one that someone had recomended in an earlier post. question could the actual gauge be defective?? also their is no sigh of the truck over heating.

 

[drabo]

The gauge can and does go bad. Some other things are, did you make sure you have enough fluid(thermostat dosen't open causing a high engine temp with no signs of overheating). Did you change it from 6volt to 12 volt? If you did I think you need an inline resistor to correct it. Actually you need an inline on all the guages but I don't know what size resistor off hand.