As suggested in the Haynes Shop Manual for 84 300D Turbo Diesel

Using a 19mm deep socket wrench, I loosened the lock nut in the steering gear box. Using an Allen wrench, I turned the adjusting
bolt CCW as far as it would go and retightened the lock nut.

Result: a noticeable small reduction in steering play but still excessive (more than 1 inch of sloppy play). I think the steering gearbox needs to be rebuilt. Can this be done? Or exchange for a rebuilt one? A new one is absolutely price prohibitive!

www.car-part.com has a few used ones. My concern however, is the quality. Can it be bench tested to ensure quality (before I buy it and have it re and re)?

BTW, all my other steering components appear to be okay.

Thanks for your help.