"5316",
In general, there is no difference in 230SL taillights between US and Euro spec cars. There is a difference between early (230SL/250SL/very early 280SL) and late (most 280SL) cars.
Early taillights are often referred to as "one-piece" or "all-red" (though there were different color schemes in other countries such as France and Italy). These taillights were not designed to have replaceable lenses; you had to buy a full one-piece chrome frame with molded-in lens and reflector. I believe that they have not been available new for may years. I also believe that there is a technique for "breaking out" the old lenses and gluing in new ones (available from some after-market vendors).
The later taillights typically have a yellow turn-signal lens section, have a much flatter profile than the original, and have replaceable lenses. These are available new, and are often used in the older cars where the originals are not available. These taillights should "drop in" to older cars - no body work necessary.
-David Pease
'66 French 230SL