At this juncture, if your D is on the OEM coolant and hoses it is time for a good PM.
I recommend new coolant, hoses, and a new T stat as well as replacing the stamped metal snout that holds the T stat in.
Mine had rust holes in it which was allowing coolant to seep out and leak down onto the PS pump.
Don't forget a good flush of the system before putting the new coolant in.
While you are at it, replace the fan clutch with an OEM unit and you will be good to go.
I have done this, and the temp gauge stays pretty much around a needles width below the middle mark. On really hot days, it might get to the middle or a width above.
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