First off, I would not continue to drive it if the temp gauge is maxing out. Bad for the engine. Depending on how steep the hill is and how much you are stressing the engine to maintain 60mph, this behavior might not be out of the ordinary. The first thing you need to do is put it in neutral at the stop light and rev the engine to increase the coolant flow through the block and airflow thru the radiator. It's also possible your fan clutch is bad and is not pulling enough air thru the radiator.
I'd also try driving up the hill at a slower speed to see what happens.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13