My car is a 1969; the tanks changed over time; I think there were carbon canisters and other sized and shaped beasts over time. This is one of those things that is ill documented in MB manuals. My cardboard filler panel on the passenger/right side of the trunk has pre-cut slots in it, and metal clips on the tank hang it from these slots.
New (as in brand new bought today)tanks have integral plastic lines which go to the vent lines on the tank. Older tanks like mine have brass ferrules and use a combination of cloth covered rubber fuel line, little clamps, and steel fuel pipe to go from the overflow tank to the fuel tank. Then of course there is the vent from the tank which goes to that funnel shaped thing, the FST.
It isn't a vapor recovery tank; it is a fuel overflow tank, much like the tank inside the engine bay for the coolant. I cut one open and there's nothing inside. Heat expands the fuel in the fuel tank, and the resulting expansion and pressure push some fuel through the lines into this plastic tank. As the fuel cools, it gets sucked back into your fuel tank.
Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored