how do I fix my 1991 Ford F250?

My truck ignition actuator is broken. this is the small L shaped piece inside the control column, that actuates a long wire arm which turns the ignition on, off, or accessorie. I had to replace the key barrel, and this actuator. I cannot see how the last two structures disassemble, so as to allow this piece to be put into position. There are two threaded opening on either side of the support ring which seem to attach this ring to the remaining support plate. If I could seperate these pieces, I could put in the actuator. Hope you can help, thanks, don