For virtual reality simulation of off--road vehicles, real--time simulation must be achieved in spite of the heavy computational load from 3D graphics generation and numerical analysis of the dynamic model. In this work, a distributed architecture was developed for off--road vehicle and implement dynamic model and 3D graphics visualization to distribute the overall computational load of the system across two or more machines. This architecture consists of three major components: a dynamic model simulator, a virtual reality simulator for 3D graphics, and an interface to the controller hardware elements. Several off--road vehicle dynamics models have been developed with varying degrees of fidelity, as well as automatic guidance controller models and an interface to automatic guidance hardware. A towed implement model and an implement tracking steering controller developed. The performance of an implement position and heading feedback controller was similar to that of a tractor position and heading feedback controller. These models provide understanding into the behavior of automatically guided tractor--implement systems. In addition, the simulation and visualization system was effectively used to examine the practical limitations that the designed controller may face and to design the controller gains to adjust for those limitations.