Maybe someone can help me with this.I was stuck in traffic in 95 degree heat and my temp gauge went up to about 220ish.I already had the cooling system flushed out.Maybe a thermostat? Any input would help.Thanks. And i also have a "53" block.

 

Overheating normally is not a problem, but 220F is hot for a diesel. At idle normally these trucks run cool 190 or so. In fact to cool them down you are suppose to idle them. Have you tried flushing the radiator (externally) with a hose? The water should run through the radiotor with no problem. NO PRESSURE WASHER! You should be able to "see" through it. You might want to use a light and see if you can it through the radiator

 

i would check the fan make sure the clutch is engaging properly

 

Look for the classic oil misting on the radiator. The blow by bottle allows oil mist to be cycled thru the radiator, then dirt sticks to the oil and bammo you are running hot. Check out mopar1973man's gallery and do his mod for eiliminating the blow by bottle.