When I first bought my 116 I had a reconditioned box installed (plus a lot of other items) when the slack could not be adjusted. Believe it or not about 9 years later I had forgotten the box was supposed to be reconditioned and thought that the slack had only been adjusted out, so when I couldn't adjust it any more I went searching for a reconditioned box, or someone to recondition mine. After getting prices I was about to buy a reconditioned box and install it myself when I thought to ask Styria what he could organise. For the same price as buying one and installing it myself Styria organised a reconditioned steering box and had it installed. It was about 3 or 4 years ago but it may pay to check what Styria can organise now.
Not sure if it is a V8 or 6 cylinder and whether it is early or late model.
6 cylinders are very easy to adjust and easier to remove. Most have probably been adjusted to death and over adjustment is one of the main causes of wear.
V8's are almost impossible to adjust in situ so most have never had any adjustment and removal and careful adjustment may be quite possible even on a box which may have substantial apparent wear.
Remove the flexible joint at the base of the steering column (Two types - early and late) , remove the ball joints on the drop arm and the box is held by it's hoses and three bolts through the frame rail.
The box is adjusted on a V8 when removed from the car by loosening the locknut on the adjuster and using an allen key and screwing the adjustor out to tighten and in to loosen (This is the opposite of most steering boxes). The amount of tightening is quite critical so unless you follow the factory manual and check the rotational torque it is best to slightly under-adjust and leave a small amount of slack.
Just be careful of what is supplied to you as 'reconditioned'. I went down this track some time back and had I fallen for it, would have ended up with a reconditioned box which was simply and old one with new seals and a paint job. I also know of other who have been unable to obtain a true reconditioned box and have gone for a second hand one and then adjusted it when theirs were worn to the point of no return.
I have no idea how much a new one might cost but it could be worth investigating.
I've just been down this track with my diff dramas, the difference between reconditioned and rebuilt is important.
If the item is sold as reconditioned it should be operating as an item in new condition, in this case the tolerences and play in the steering box should be within spec and have a degree of adjustment to compensate for wear.
If it is rebuilt then you get seals, the damaged part repaired and a paint job, complete with yellow paint dabs on the bolts and seams to prove it was rebuilt
As I discovered with my diff, the fact that the word reconditioned appeared on the invoice saved me from much financial pain by cementing my case.