Go with the MOCO parts, It's called Touring Detachable Rear Docking Hardware Kit. You have to get the front and rear kit. It maybe listed for up to '03, but should fit the '04 models. Don't believe there were any changes to that area of the frame. Try doing a search, several here have done it. For just the Tour Pak you'll need;
Tour Pak Rack Part #53107-96
Front Kit Part # 53104-97A
Rear Kit Part # 53127-96B
also recommend the laydown plate holder.
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