[klayfish]

Terry,
Not to take this off the topic of insurance, but be very careful how you do this. This has come up before, but companies like Titles Unlimited, who will "change" your title to a 1965 are very dangerous to use. Most states consider it to be title washing and is illegal. You can get in a lot of trouble if the government decides to crack down on you.
As for the insurance, tell them VERY clearly in writing that the car is a 2003, and show them paperwork. If your rates are lower because it is titled as a 1965, you must disclose to them that it is a new car. If something were ever to happen, then the insurance company can't come back to you and say you lied to them to get cheaper insurance. You can show that you told them it is a new car, and it was their decision how to charge you premium. If they still decide to insure it as a 1965, that is their choice, but you made them fully aware of the truth.
Best of luck and be careful.

Steve