I'm still pretty sure it's from an exhaust or muffler system of some kind - thought we were on the right track with the Panzer IV, oh well... It's worthy to consider that kit manufacturers don't always model their parts exactly as the real thing should be (shocking...!!!) so it still could be from a Panzer IV kit, just not a very accurate one....
Plus the part in your pic above with the red arrow looked different than the dark green one in your first post, I didn't see the small bit protruding from the middle of the main tube. That may help in the identification.
Also, here's a Yahoo Group that's dedicated itself to Scratchbuilding the Millenium Falcon. It lists a lot (maybe not all) of the kits and parts used by the model builders for the Star Wars movies. You may find what you need here:
http://groups.yahoo.com/group/MFalcon/
Bob