Tulsa, that is all I remember, believe he worked at a rental place for equipment..
getting back to your truck, I am sure this may not be the problem but it wont hurt to check,,,,,,,,,,make sure you do have the radiator cap on tight..........seems strange that it would lose that much coolant and not show the temp heating up...
usually with fresh 50/50 coolant you can find the external leak real quick, either see it or smell it...
you have replaced and covered most ever thing it can be, unless the timing is off, I have never seen this happen myself but folks say it can...
make sure the radiator peacock is tight..
let us know when you find the problem..