The GT pumps are not a direct replacement for the GT500 pumps. They are shorter, have a smaller diameter, and the outlet is smaller too. The manifold on the top of the stock pumps will not fit and create a seal on the GT pumps because of this difference. You will have to route some fuel lines in the tank and create a Y to connect them to the discharge on the hat. The connectors are also different. It can be done as we've done many, but there is some work involved.