2015 Ford Expedition has slight vibration when towing at highway speed.

First of all towing a trailer at 70 is nuts. That’s called torque converter shutter. Using too high a gear when towing, were you in the top gear with the trailer attached? Doing 70 that is most likely the case. That’s a good way to wipe out a transmission, keep the speeds down and stay out of any overdrive gears while towing. You have shortened the life of your transmission but it’s hard to say how much. Check the transmission fluid level and color, and just hope it is still a bright red in color, if not get it serviced right away and you might get some more time.

Answer not posting

Universals going bad ? Yolk bearing in the differential ? GA Will probably say close to that , don't know why posting can be a problem .

Every time I answer more that three questions in a session it always does that. I have to either change computers or wait an couple hours. U-joints should be apparent all the time. However a driveline carrier will cause a vibration but it will be noticeable at one speed then back, off and then come in again at a higher speed. Pinion bearing will cause a vibration but also noise that would be almost intolerable.

Yep did it again.

Could be lock up torque converter shudder. The trailer will change the load on the drive train making it more noticable.

Thanks for the input everyone. I'm thinking the trailer was heavier this trip than previous - perhaps too heavy. I've emptied the trailer and will give it a tow on the interstate soon. Bob