On trip....tranny failing....help

[smokdout]

I drove up from Central Florida to the ATL for work on my PhD. After about 2 hours on the interstate I noticed my tranny temp gauge on my dash was pegged. My Auto Meter gauge revealed that the tranny temp was normal. I stopped at a truck repair shop (shady) where the guy ran the code and it revealed that it was possibly a sensor in the tranny and I would be ok to drive. So I get back on the interstate and as I tried to get up to speed the truck would not shift into overdrive so I could only drive at 50mph. Another 30 minutes passed and the truck for whatever reason shifted and I was able to complete the last 3 hours of the trip. While in Atlanta yesterday and today the truck feels like it's shifting fine but the dash tranny temp gauge pegs after only a few minutes.

I have already ordered Ams oil synthetic and a Mag-Hytec tranny pan so it will be ready when it goes in the shop next week. Any thoughts on what I should expect to hear from the shop.

thanks