[billnorman]

You are one hard working man! However, you should repair the thermohousing before you replace the fluid. The fluid looks to me as if it has caused corrosion and deposits in your radiator and system. Be careful where you dispose of the used anti-freeze as some types are very poisonous to pets, and they like to drink it. Nothing will make you more hated by your neighbors than killing their pets. I am not sure if your truck uses an "o"ring or/and a paper gasket, but you should clean the surfaces of the housing and use good bolts and nuts to retain it. Make sure the housing has not warped from overtightening if so, make it flat again.
Sometimes electrolysis causes corrosion in radiators, but I don't know how to cure it except keeping clean anti-freeze in it. Your photographs, as usual, are great, but they do make the radiator look rather dirty inside. I'm afraid to look at mine.