1-Ton Dually for $1600? Hmm, what can I say about this. Z6, just a suggestion here, but maybe try for something more main stream with parts that are going to be cheap and available from the auto wreckers or parts stores. Duallies, If I'm not mistaken have floating rear axles with very "unique" parts that are hard to find (even brake drums) and the expense to even do a rear brake job will almost be the cost of what you pay for it.
Front brakes and rotors are a different beast as well from standard GM parts and more expensive. I think "economy" like a reliable Toyota or something is what I would be shooting for when I'm going to school Z6, I think that dually will sink you faster than the Titanic in Fuel alone. Either way, the decision will be yours, your paying the bills Z6 not your friends. Just a thought for what it's worth.