careful here.
A 230SL has a fluid coupling. It is a short aluminum cylinder about 3 inches (8cm) thick and about 12" (30cm) in diameter.
On later cars, there are both torque converters and fluid couplings, and there are two kinds of fluid couplings.
Later fluid couplings are iron and have a rounder shape to them. Torque converters are also iron and have rounder, oval profile.
The difference between them is that a fluid coupling has a single set of splines to hold the input shaft of the transmission and the torque converter has two concentric (circle within a circle) sets of splines that mate to both the input shaft AND the pump housing.
If your mechanic intends to keep the current transmission, make sure it is the one that is matched to the engine (the M130E motor should be matched to a transmission from either a 280SE or a 280SL) AND make sure that you know if it needs a torque converter or a fluid coupling (and which of the two fluid couplings).
Once you know the specifics of what you have the other parts are easily acquired in the US, but shipping will be expensive. The parts can also be acquired in europe from one of several good used parts suppliers.
-CTH