The newer spare tire carriers' handle and front mount are angled so you can get at the handle more easily. Because of this, you may have to make some mods to get it to fit.
You ARE talking about the spare tire holder that goes under the tongue that you get from Airstream, right? If not, nobody will be able to help you without at least photos.
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.