One of my fog light outer lenses fell off?

[Jughead]

How easy is it to replace? Will I need a new lamp too?

 

[Vipersix]

Fog lights are normally pretty straightforward and easy to replace. As long as you ensure that there is no moisture in the new fog light and you wipe off your lamp as best you can you should be able to get away without buying a new one. Moisture is enemy #1 for those stinkers.

 

[BYRDPE]

Same thing happened to me.
Got a new one from 5.0 resto for about 29.00.
http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=LRS-15200A 1&comp=LRS