1997 Powerstroke 7.3 Runs rough

Alright i need some help on this one fella's.
My buddy called me up yesterday, he has a 97 f-250 7.3L Turbo diesel. He tells me it shakes pretty bad at idle and slow speeds, 5-15 mph. I'm thinkin its a motor mount but i need a second opinion bein as i hae little experience with the 7.3. Thanks a bunch.

Ps- My buddy lives across state so thats why he "called" and i didnt "see".

Thanks again
Chris