Have a look at [broken link removed], which outlines stamp duty clawback if you rent the property within a certain period. They changed it last budget so that you can rent once 2 years has passed (the wording is slightly cumbersome, but that's the general idea). If the clawback did apply, you would have to pay the difference between FTB stamp duty rates and investor stamp duty rates.
So yes, if you bought in 2004, you shouldn't be liable to stamp duty clawback if you rent now.
All the best
Sprite