A car, usually from the 50's (i.e. 49/50 mercury, 49-54 chevrolet) that has had custom work done to the body. Usually peaking, chopping, skirts, lake pipes etc. that involved finishing/molding with lead - as in the days before Bondo. Rapdily a lost art, leading is still practiced by a few who appreciate the longevity and other issues present with a modern filler.
Look at that cool 50 Mercury with the frenched lights and lowered lid, that's a real led sled.