Im pretty sure your right about it being a cavielar rack/I found a kit that you can rework the old flow valve for $17/have you ever used one of them?beats buying a $100 adj valve/If any one has used the rework kit on a old valve did it do the job for you?

i make a rack kit my name s@t fabrications i sell mostly the 57 -59 and i do make 55-56 what i use is the cavielar rack because it is set up for rear steer the mustang is front steer so im thinking yours is the same as what i use the easiest thing i think you could do would be to put a adjustable pressure valve in the high pressure line you will get the feel you want sparky

Sparky

 

First some history I purchase this 55 fairlane over a year ago/the previously ower had a aftermarket power steering rack and GM pump installed/for the most part it works fine except  it is twitchy and darts to easy/I found a tech tip that says if you have a mustang II rack with a early GM pump replacing the 3gpm valve with a 2gpm flow valve will  take care of problem/my problem is how can I tell if this is a mustang rack and a early GM pump/any help would be appreciated