This is the one I have and I love it...

 

Schumacher-
You are correct....this one will not work on an '03 model Softail. It's made for the '06 and later models with the 200 rear end. Check out the Kurayken Pancea tail light. I had one on my sporty, and on my FXST. I've really liked them. They're the same size/shape as the stock light, but they're LED and have built in turn signals. This frees up the rear end of those blinkers that hang off the sides, and allows you to run with detachable backrest hardware easier.

 

Hi Schu,
The light your looking at, the Tri-Bar is what I have on mine and I like it a lot. But unfortunatly beaureed445 is right, it only fits the fender on bikes that have the 200mm rear tire, 07 and up.
As a second choice I like the Paul Yaffe, and unlike the Kuyre light that just replaces the stock light with another of the same shape. It at least fits the contour of the fender and doesn't look like an afterthought.

 

get rid of the tailight and the turn signals and just put a side mount on it. Then lower than pig.