Just to get this straight, silver ECHO freewheels (except the very first gen. with black lockring) were the old "SL" model. Gold color is the current "SL" with titanium driver+lockring and steel outer ring. black color is the "TR" freewheel.
The fact that some dealers create their own names for components such as "SL 108 black" (=TR), "SL 108 silver" (=old SL) and "ECHO Titanium" (=SL Ti) freewheel doesn't help in this discussion.
same story with echo frames. The model names "ECHO Lite" (="ECHO 20") or "ECHO Pure" (="ECHO 26") were stopped before 2011 but I can still find them being used for 2011-2013 frames.