NEW LED Lights installed last week. All I can say is WOW, they are so much better.
I installed them to get a lamp unit that is totally sealed, to avoid water getting in to the lens, then run down the inside wall and rot out the wall.
These are the lights I used: Sealed RV LED Marker Lamp
Here's a few pics of the old lights:
The incandescent lamps and their removable lens, I have seen water and dirt in get in them. If the water doesn't drain out, then water will fill up and leak past the lamp socket and down the wall. This issue seems more common on the front wall marker lamps, which are subject to "water injection" when driving in inclement weather (heavy rain)