1998 Nascar Edition stripes now reproduced
 

My wife and I bought one of those trucks last week and the stripes on ours still look like new, but in doing some research I came across a supplier of replacement stripes at this link:

Ford F Series

If you scroll down that page you will see it. There is a pull-down for the whole package listing. At $500, it might be less expensive than having the whole thing custom done with paint at a shop.