you need to jack the back end of the truck up , operate the steering , identify whether there is any play in the steering and resolve this. Once all the mechanical checks have been carried out e.g king pin play etc. You need to adjust the steering stops. Failure to adjust the steer stops correctly will lead to excessive loads being applied to the wheel hub bearing when driving or reversing the truck with large amounts of steer angle (ackuman's principles of steering & basic physic's).