Temp

Ok guys, this may be a stupid question that has already been asked and my phone won't let me search, but what is the normal operating range in degrees for a 2600 I just put a new mechanical temp gauge in my truck and I'm wonderin what is max temp for my truck? Right now I'm running a 180 thermostat. I have been having problems with overheating lately and I don't trust the stock temp gauge on the gauge cluster. If anyone could help me out that would be great. Thanks in advance for the help.