I am putting the column back together on my 71 CUDA and I can't remember if a screw was holding in this piece which is the block off plate underneath the flasher switch where the key lamp would go if you had the light package. I did not take a picture of this before I took it out of the column. The side of the hole not seen in the attached pictore does not look to have had a screw head against it and the casting doesn't look like threads were in it. It seems as if the flasher switch will hold this plug in place even if turned on.

I'm curious what others have found here.