The shakes at 70mph - 4000

[Michel John Wendt <mwendt@csd.uwm.edu>]

My '84 4000S with 122k miles gets periodic shimmies (vibrations felt 
through the steering wheel) at or above 70mph.  The condition happens 
only occasionaly - it seems to occur after running over a 
particularly rough expansion joint, but can also happen on a smooth 
surface.  It stops as soon as I let up on the accelerator or move the 
steering wheel slightly to the left (to the right seems to make it worse).


Any ideas?  

The car was aligned recently, but is in bad need of a new set 
of shocks/struts.


In advance, thank you.

Mike