Hey Felix. Try posting your question on the Lindsay Cadillac board. Their parts guy (Luke) is very helpful. http://www.cadillacforums.com/forums/lindsay-cadillac/
Also, you might check with junkyards in your area to see if you can get the cap off a wrecked CTS. Good luck.
Also, you might check with junkyards in your area to see if you can get the cap off a wrecked CTS. Good luck.