It's a Custom Chrome. (part# 14093) It looks like it is no longer in their catalog.

I did find one for sale on ebay for 39.95 plus S & H.

http://www.ebay.com/itm/Swingarm-Mounted-License-Plate-Bracket-for-FXST-Softail-/370702482803

In a civilized country, wild animals only continue to exist at all when preserved by sportsmen. The excellent people who protest against all hunting are ignorant of the fact that in reality the genuine sportsman is by all odds the most important factor in keeping wild creatures from total extermination.

Theodore Roosevelt