74 duster

If you see the little hole in the column where the unlock pin goes (assumed to be broken/missing), perhaps a tickle with a small pin-tool will release it?
I had a 73 and a 74, but both with autos. The interlock button was close to the ignition sw. but on top IIRC. Also IIRC it was still a more-or-less two-handed deal.
I hated those and ripped 'em out ASAP. I put in my own stinking anti-theft system. I park my car almost anywhere now and leave the windows part-way down, and the doors unlocked. It's never gone missing.