Visit a CHROME shop are you planing on replacing the lens or the entire light??
If you can not find the lense get an LED marker/running light assembly that is slightly larger than the existing and replace the entire assembly.
What is a "Chrome Shop"? Bling for Truckers.. Look up the I-90 Truck stop in Iowa on Interstate 80 It is ONE of many such shops scattered around the country but it will give you a clue as to what to look for... Largest in stock selection of lights I have ever seen was the I-80. Other "Chrome shops" are not far behind (if not better, I've only been to a few of 'em and one was .. a long long time ago).