How's the trans temp since radiator cooler by-passed? I saw earlier in post that MEngr has experience with this model overheating-what generally is the problem? Did this truck always run hot or did these symptoms come on out of the blue?
What type of enviroment does unit operate in- hot & humid? I know you said that the cooling system parts have been replaced, but were they inspected against the old parts when replaced (radiator core size, fins per inch, # of rows of cooling fins, waterpump vanes in correct direction. I've had waterpumps with the wrong direction fins (presumably for a serpentine belt set up)). Do they have other units of this model at this location?