If it's a readily available cover you're looking for, a Mazda Miata cover fits perfectly; nice and snug. I'm using one on my ERA 427SC. I'll have to shoot a picture of my car covered and put it in my gallery.
What's funny when using the Miata cover on a Cobra are the pockets for outside rear-view mirrors. They sort of flop out in the wind with nothing to support them. They do mask the fact that there's a Cobra underneath.
