This E-Bay ad has a photo of a 124/190D tank:

Mercedes Benz W124 W201 190D 190E 260E 300TE 300CE 300E Expansion Tank | eBay

The level sender and the outlet both point forward. On a turbo, this puts them in the middle of the air cleaner. The turbo tanks (2015000249 or 02015000549) have the sender on the side of the tank, and the outlet angled out of the bottom. There is a tank that was used on the big 124 v8's, 1245001549, which may be a workable substitute. But it cold be an expensive experiment, even though they cost half as much:

http://www.ebay.com/itm/Mercedes-w124-400-500-Coolant-Expansion-Tank-GENUINE-OEM-NEW-1-YEAR-WARRANTY-/301660117787?hash=item463c581b1b&vxp=mtr

The beer can fix sounds interesting, but I never drink...beer.