Before spending money to reseal your old steering box, first check the amount of free-play in your steering. If it exceeds 25mm at the steering wheel, the box is probably worn and worthy of replacement.
Replacing my front and rear links, rods, bushings and dampers improved handling only marginally. It took a new steering box to really make the difference in regaining the handling confidence/sureness that's so characteristic of this design. In short, the steering box is a critical component in this model's handling -- and after 15 years of average mileage you can expect some wear, which should be checked.
Fyi, I paid less than $1,000 Cdn ($650 US) for an MB rebuild installed by my independent (not that much more than a resealing job).