4.7 Transmission problems

Hey guys I have a 2007 with the 4.7L v8. I’m having some really weird issues go on with my transmission and want some guidance on where to start. When I bought the truck the previous owner put a new remanned transmission in it and he said it had about 30,000 miles on it which matched up with the carfax report. Soon after purchase I needed a new trans cooler. And then recently I was driving and the trans would not shift into 5th. I pulled over and instantly got it towed. The dealership told me I had metal in my transmission fluid and that the transmission would need to be replaced. After getting the truck back it drives fine but won’t go into 5th I’m very skeptical that the transmission needs to be replaced as I had it at a different dealer months prior and they were the last ones to touch it and add new fluid. They told me it was driving great. Just wondering what my options are and where I should start with diagnosing this issue. I’ve heard grounds, valve bodies, or even the harness. The other thing that I don’t understand is there is not a single code for anything that I can find.

 

I'd take it to an auto parts store and have them run diagnostic tests with their top-of-the-line fancy machines. They may be able to pull more codes than the regular obd reader you may be using. Without codes people are just stabbing in the dark, my SWAG is that it's probably not your transmission... It's probably more to do with electronics, shift solenoids more specifically.