change them all

you will still get change from a fiver if you buy them direct from ford

there are 2 plastic bushes, inner and outer

there is a rubber cover that goes around them to hold the outer one in place
then there is a metal cover to stop the grime

and don't forget the metal disc locking washer that goes on the column too

if you are flexable you can swap them over in about 15 minutes, just make sure you don't have the engine running for about 5 hours beforehand as, depending on what car you've got, it's VERY close to the exhaust manifold