Actually, The photos posted above are not the replacements. The replacements have two bulbs which kind of look like two "bull eyes" one on each half of the lens.
You can buy them at Wal Mart for much less than the RV stores are asking. The units are typically plastic based but you can buy the cast metal based ones from any trucking supply store or truck stop.
The cast units blend a little better and they are not effected by a solvent such as paint stripper. The lights come with one connection and ground to the skin via the screws that hold them in place. They are a Grote product but the lights are manufactured by several manufacturers including Signal Stat who is now Truck lite.
Th old units have a metal receptacle which in time lose there retaining "spring" The new ones are plastic based and come with a light bulb that resembles a Yard light bulb, All glass with no metal base. Last a long time.
The replacement cost around 3 dollars each at Wally world and you can pick them as cheap a 1 dollar at Harbor Freight tool stores and truck stops.
Been there done that many times.