My 1990 F250 has the 3 inch rear shoes driving me whacko, I can't get the shimmy out I tried different shoes- junk and Motorcraft. Took it apart put it together any one else had this one WTF??

 

It's possible that one/both of the rear drums are warped, this will cause the steering wheel to do the shimmy-shake-shake, known as "brake judder" in the biz.