What I do is use the russian site to figure out the part number needed.
russian site: Óçëû è àãðåãàòû
Then I use the part # to get the part. Most of the parts are the same between say a 280ce or 280e and the sl or slc. Mercedes shared the partsbin for many parts, they used a lot of 107 part #s but you'll also see 126 and 116 #s also. The only part I ever had to take back was the rear flex disc b/c I said 450sl and that has a different drive line and the brake pads without sensors.
It really isn't that difficult to find parts if you know what to say, it is hard to explain that you have a euro car and the parts might not be the same. If you don't wanna mess around go to the dealer with your vin and they can hook you up, but it is costly.
Good luck finding parts, you'll figure it out.