Thank you for the reply. While I do not have any source material on the NC-123B avionics suite, I presume that this could have been related to the ROCAF C-123B of that vintage, which were also used for special ops in SEA. The main difference was the primary nav system, since the ROCAF Providers were equipped with Omega instead of Doppler.
The photos of the C-123B/Ks available online suggest that the Providers were indeed equipped with the ARN-6 ADF, but perhaps also with VOR or TACAN DME. That's why I still count on someone's flight manuals library.