You likely need this: Shimano 105 Flightdeck St 5500CA Right Side Plate Front Cover | eBay

However there are only 2 hours left in the auction as I post this.

And no, Shimano no longer makes this part. This was discussed recently here:

http://www.bikeforums.net/bicycle-me...me-plates.html

I see you are new here so welcome! I'm sure others, like Andy, will chime in and tell you to use the search function.

There is a guy on Ebay who has made a similar plate with a 3D printer and is considering making these for the 5500, 6500 series shifters. I can't seem to find his ad at the moment. But If you give him encouragement it may expedite his interest to do so.