i have a 2003 impala it has been shifting hard

yeah it will go in the gear inside the car it will just will not go when i put it in a gear .it will go in all gears inside the car but it will not go when i put it in a gear.

If there is nothing wrong with the shifter cable to trans. which it's a posibility but doubtful there is something wrong internally to the trans. and it needs to be diagnosed by an auto shop. If the trans. needs to come out have them replace hte pressure control solenoid. If it isn't what was causing the clunking it will go bad as they all do. It's a few dollars more for the part but should cost you no labor since the trans. needs to come out. Sorry for the bad news and good luck. Be sure to have it diagnosed by a mechanic as they can actully get there hands on it rather than someone like me that can one get on a keyboard and give you a diagnosis based on words.