Canadian Champ

My 2012 fusion 3.0 sel awd shakes violently between 30-60 km/h smoothens out after 60k , runs great at hiway speed. had some small oil leaks on driveway.took to mechanic , PTU was empty he filled it and wasnt 100% sure if it was the driveshaft , PTU or combination of both . Been 2 months and no leaks but same vibration between 30-60km/h . Don't want to start part replacement until sure. ANYONE ELSE have or fix same problem? any advice? thanks