Master cylinder rod seal / grommet

Need to give more details. You didn't state car model and year, if manual or power brakes, and what "new one" and "it" part you are looking for. People here assumed "it" = "bushing", but then you mentioned "grommet". After I tore up a new rubber bushing in a "test fit" (yes, it locked into place well in the 99 Breeze MC piston), I bought another bushing. Can't recall if a onesy ebay or a specialist brake vendor like Dr Diff. I haven't seen the rubber bellows "dust cover" part sold alone, which I assume is your "grommet". But, many new MC's come w/ brake rod installed in the MC w/ bellows, all for ~$30. I know I have seen for my early A's on rockauto. Should fit your car, regardless of year, as long as an A-body.