Question on thermostat in Cummins Big Cam IV?

If you have followed any of my post's, the past few months, you already know I have a 1988 Pete 377 with a Cummins Big Cam IV in it. Havent used it very much at all, as it has been in and out of my shop fixing things to get ready for summer wheat harvest. I did notice when I was just "bobtailing" around the temp gauge would run between 150-170. Yesterday I hooked in onto a 30 grain trailer to haul some soybeans to my planter. Today, I was bringing it home, empty of soybeans, up and down a few small hills, for a total of 20 miles. I noticed along the way, the temp gauge started creaping up to just below the 200 mark, I would say maybe 190, and stayed right there. I can remember on my old IHC I had prior to this truck(with a cat motor), when it reached 200 degrees, it wasnt long after that I was pulling over to the side of the road as the motor shut down. My question, on this Cummins motor, what is the typical temperature operating range? I had plenty of pedal left under my foot, and it was not lugging at all.

Another question I had about this truck, is there is no manual throttle control. I have not seen older semis like this, without a manual throttle control. Is this odd, or normal? I have another 1988 Pete 377, and it has the manual control by the seat.
thanks,
coadman