You can replace just the bulb and I can highly recommend a red led for this, looks much better than the green one.
Re wishbone bushes, easiest way to remove them is to cut them flush with the wishbone both sides, then it easily comes out, even if it's 30 years old, never replaced and super rusty.
1996, 3.2 SWB X300 - Finally a rust free daily driver
1997, 4.0 LWB X300 - Unlucky car.
1988, 3.6S XJS - Never ending restoration project.
1994, 3.2S X300 - Accident damaged, October 2015. Gone!
1994, 3.2S XJ40 - Long gone.