yes there are 3 flavors of slotted rim.
First off: the basic cop wheel. Has the nubs for the dog dishes. 15x7
Next up: The Magnum GT wheel. Looks a LOT like the cop wheel, but no nubs. Also 15x7
Finally: The rarest and most expensive flavor, the Super Coupe wheel. 15x8
Magnum and 'Coupe wheels requre center caps. And Rally wheel centercaps won't fit, without a little grinding/machining.
I've got a set of Magnum GT wheels, they don't go for much when you find them. Super Coupe wheels tend to be pricey though...