How to tell your transmission is going out dodge durango.?

I have a 03 dodge durango. And to day I was driving going 55 mpg. And then It stop on the road. Here are the sign the car is making. The rps are going up and down. The steering wheel locked up. And it will only go to 30. Do you think that is the transmission? AAA brought it to the auto shop. It was hot out to if that makes a difference