Thanks for the insight. Yes the noise is only there in 3rd and 4rth. It is not there in reverse or 1rst or 2nd. The noise sounds similar to when a pinion bearing is bad in a diff but it is for sure coming from the trans. It is pretty loud and can be heard outside of truck if it drives by you. When the trans shifts from 3rd to 4rth the speed of the noise changes with the shift.