Where can I find matching connectors for my steering column?

Junkyard is your best bet. I don't even know the name for that style connector. I have seen those 1-row connectors on a 1974 Dart (JY). The collapsible steering column (mesh) in the photo says 1969+ (at least). Around 1972, they moved the ignition switch to the steering column, so needed many more wires. My 64 & 65 use a 2-row connector ("twin-lock"). Check 1980-90's motorhomes since they have many of the earlier connectors and are rarely picked at the junkyard. It seems Chrysler used up their discontinued parts in the motorhomes, or changed their designs less often.