I’ve changed 2 trailers over to LED. Both times changed complete units. If your trailer has the sealed units that mount in a black rubber housing you should be able to buy lights that fit the housing and plug right in.
Hi Jon,
I’ve replaced both my taillights on my 2002, I think the 2003 trailers have the same lights.
They are more squared off but Northern sells a 2 tail light LED kit, you’ll probably need to drill out new holes to attach them to the fenders but they fit well. http://www.northerntool.com/shop/tools/product_200338570_200338570