Driveshaft shake when driving after 35 mph down the rd,coupler was replaced and

What is your question?

After the coupler recall on my 2015 t250s 10,000 miles later I am getting a terrible vibration and howl,I brought it back to Ford and they told me the front or rear driveshaft is out of balance,they told me for the 3rd straight day they are waiting for parts availability?And it is not under warranty. I have a company and bought 15 transit T-250 s,The vehicle has 105k miles and well kept,if I do not get satisfaction I will bring everyone of the Ford Transits to a gm dealer and trade them and never buy Ford again

What makes this problem better or worse?

Nothing

How long has your 2015 Ford Transit-250 had this problem?

On and off after 35,000 miles