Thank-you all for the help!

The truck had a code "P0633 SKIM Key Not Programmed in PCM" Not related and a non issue.

The trans fluid is still red, but I'm changing it anyway.

I drove from CA up the grade to Victorville and then up the Baker grade and it didn't get hot like this. Then when I was in Vegas, the road was much flatter. There was a wind and that's when it got real hot.

The truck is a early 2003 build, not the HO. I replaced the front cooler with another OEM cooler because its 14 years old and I'm not sure the thermostat in it was working. Those tranny lines are a pain to disconnect from the cooler. Flow test is next...