904 Column Shift Linkage Grommet Installation

I'm having a heck of time reinstalling the shift linkage in my 1974 Dart. I blame the headers.

This last grommet circled below in grey is the holdout. I bashed and bruised my hands, tried above and below the car for over 4 hours yesterday and could not get it to pop in. I think I'm missing a tool or technique, it can't be this hard.

Any advice you can give would be most appreciated.

904 Grommet Installation.jpg