I wanted to buy a new radio for my 2004 silverado. I was told I would have to have the radio reprogramed by the dealer with the new vehicle VIN number.

Is there a way I can do it without having to goto the dealer?

You say you are wanting to buy a new radio but you do not say if it is an after market one or a stock replacement. If it is an after market one, there is no need for any kind of reprogramming.