Here it is:
http://cgi.ebay.com/ebaymotors/Mercedes-Benz-300-Series-350-SDL-Turbo-5-Passenger-Sedan-Light-Ivory-Yr-1991_W0QQitemZ4602774468QQcategoryZ6330QQssPageNameZWDVWQQrdZ1QQcmdZViewItem#ebayphotohosting
The seller has a perfect feedback rating. That's in your favor.........but...........how long has he owned the vehicle? At one point he states that there were two prior owners...........in the questions he states that he put 170K on the vehicle???
One quart every 2K miles doesn't sound all that comforting to me. It could be any number of little things........or it could be the big one........or it could be burning a quart every 1K miles.
Let's see what other folks have as an opinion regarding it. However, it's a crapshoot no matter how you look at it.