I'd check in and call somebody ( or an old prosthodontist in your area). I tried to look it up, all the "narrow neck" things I searched for in their shop shows the NNC connection which is a narrow-neck-crossfit but this isn't what you are looking for here. I doubt there is a modern digital solution for this; it's the rare Straumann ëxternal hex" type solution which may have been rebranded as "Straumann Classic" at least in the Australian e-shop.
Good luck!