I have a 2002 Explorer XLS 4.0 4x4 that has a strange rough shifting issue. It is very intermittent and only shifts rough after the vehicle load changes. I may drive all week by myself and have no issues then drive to town with the wife and kids and it runs fine, but shut it off and drive it and it will shift hard on acceleration. If I turn it off and restart it's fine. There has been no engine codes saved and no check engine light. I was told by a transmission shop it is sensor related and the speed sensor would be a good place to start. Does it have an input and an output sensor and where are they located? I know there is a sensor on the rear diff. is this what I'm looking for?