Column shifter linkage...HELP : )

The piece you have the circle around bolts to the frame just below the column. Although in the picture it's bottom side up, the bolt hole goes to the bottom and the bracket the shaft goes through goes to the top. it's held to the frame with one bolt the tab fits in a hole in the frame to hold its position.
Unless I was to remove the bolt on mine to check I'm not sure of the size but it appears to be 3/8-18.