Sloppy steering

Last year I had the problem with my Imperial having sloppy steering and what I would call "white lining". That is when you're on a straight road and the tyre hits the white line in the centre of the road it will throw the steering out. I thought at the time that it was a tie rod end. I was right, but also wrong. Not only was one of the outer tie rod ends worn, but also the inner tie rod end on the opposite side was as well, as well as the drag link bushing. As for your car with 73,000 miles on it, that is irrelevant, its due to the time that the car is laid up, i.e. not driven. Time itself is the biggest killer of the man made materials that are added to the vehicle, such as bushings (for the last two years on the run I have had to replace the sway bar/torsion bar bushes due to inferior materials and wear). Even the grease which is packed in the tie rod ends (how many people replace the grease nipples to ensure that they have not become clogged and dried out over time). The new steering box that you had fitted five years ago, although could have been the main cause at the time, will only highlight any weaker areas on the steering system and also will put more stress and wear on joints and bushes. A good example, when replacing clutch discs in transmissions, you don't replace the ones you think are OK. I have myself a lot of knowledge on this with building a lot of hydrastatic machinery.