Mark,
Many thanks for your reply -- my one remaining question has to do with the
flexibility of the two sides of the linkage.  On my bus, I loosen the clamp
and the joint doesn't move front-to-back.  I can swing the whole linkage
side-to-side (when in neutral; this causes the gearshift lever to move left
to right); this makes the front shaft turn in relation to the rear shaft, I
think.  I've been loosening the clamp, swinging the whole assembly left or
right, and tightening back up.  Is this the kind of adjustment I'm after?

Best,
d.