[Arran]

I have a theory that regardless of the production number itself, the fact that they were higher end sets, both in performance and price, meant that they were looked after and maintained more so then a cheaper set. The kind of people who could afford a 38-116 were likely older to start with and could also afford to look after things. The fact that they also made 25,600 of them as well probably explains why so many seem to have survived, while that isn't anywhere near as many produced as lets say a 40-180 it's still a lot for such a high end set.
Regards
Arran