cab and chassis or dually?

[bagged01extcab]

I just bought an 85 4 door crew cab 1 ton with a work bed on it, and was trying to determine if it was a dually or a cab & chassis. How can I tell the difference? The brake hubs are right up next to the spring perchs, and It looks like the outer wheels stick out past the rest of the body, but I'm still unsure! Maybe someone has some deminsions or something! Any help is appreciated!

Thanks