if you have or had travel when turning the steering full left or right but not anywhere in the center that sounds like a problem with the sensor board that is mounted on top of the steering axle underneath the control panel.
the 2nd thing that comes to mind would be the directional contactors or the logic card , possibly some connection issues there but if the motors were turning in fwd and reverse when turned left or right then that leads me to think something wrong with the steering position sensor board.
Try running the onboard diagnostic and see if it will pass the steering angle sensor test (test 5).
Hopefully the schematic is still underneath the hood, if so it has all the instructions on how to do the onboard diagnostics.
make sure you remove the drive fuse before the test, it will tell you to if you dont ;o)