I have not had the chatter, but had my rack replaced under warranty for a
leak.  Ford got 500.00 for a rebuilt rack.  They are availalable in the
aftermarket rebuilt for less than 1/2 that.  Saw that rockauto online has
them for some models.

May want to change out your old fluid and see if that helps.  Changing P.S.
fluid is something almost everyone ignores, and at some point it gets old and
tired.

I got rid of a pulsation in my steering by using Mobil1 synthetic ATF. Change
your fluid, drive the vehicle for 10 minutes, and change it again.  You can't
drain the old fluid in the rack or the line from the pump to the rack, so
there will be old fluid that mixes in with the new when you change it.  The
second change is to make sure you get 75 to 80 % new fluid.