Got a '96 2500 with 12 valve Cummins.  The water temp gauge was slowly
walking back and forth between 0 to 190 degrees F.  I took it to the shop
- they said it needed a new sender.  Got it replaced.

Now, the temp does not walk up and down - it reaches a steady state at
about the 10 o'clock position and stays there.  The 12 o'clock position is
190 degrees F.

I'm told diesels are cold natured, but shouldn't this engine be regulated
to 190 degrees F thru the thermostat?  Normal air temps right now are
in the 90's....