My Power Disk Brakes are frustrating me...

I just read your post about the brake booster. I have same issue. I bought the adj push rod. From mancinis. I removed everything booster brackets and the power push rod. The question I have is the original bolt that connects the push rod under the dash is bigger than the hole in the new push rod. It came with a rubber grommet. Does this mean I need a smaller bolt? Don't understand why the kit doesn't come with one.