My 300D Is Wandering All Over The Road

I recently purchased a 1984 300D. It was a one owner vehicle, and, in general, was well maintained. However, the car wanders all over the road! The front tires are worn and feathered with high ridges toward the outer edges. I looked at the front-end last night, and the upper control arm bushings look okay. The lower ball joint boots are torn, and, therefore, need replacement. I understand that worn guide rod bushings can contribute to the wandering problem. I'm willing to tackle the ball joints and replacement of all of the bushings, however, before I start I want to be sure that I don't actually have some type of steering problem, as I'd hate to invest the time and money and not solve the problem! I would appreciate any input anyone would have as to how to properly diagnose front end issues with this vehicle.