Anyway, with the passing of time, microphones improved and it was no longer necessary to drill a hole in your saxophone to connect a pickup. The trouble is, horns that were played professionally, horns that were loved by accomplished players, horns that were "keepers," sometimes had a hole drilled in them for a pickup. It seems odd now that you would love your sax so much that you decided to drill a hole in it. A lot of really nice horns have old Vox fittings soldered on the neck.
One could choose to leave the fitting in place. But there is a problem. The fitting came with a little plastic plug to be fitted when the pickup was removed. Either from the passing of time, or maybe from when new, the fittings leak a little. You can use a suction test and see that air passes through, or you can put soapy water on the fitting and blow bubbles. Not good.
Here is a Vox fitting on a 1937 Conn 10M neck. A hole is drilled in the neck even with the upper octave pip. I'm not sure if that was what the manufacturer recommended or not. I'm not sure why it had to be there. I think that having a cable connected right in front of the mouthpiece would be about the worst place to put it from a player's point of view. Whether it was best from an acoustic point of view?