First you need to put the valley pan gasket in place without the end seals.Then measure the gap from the bottom of the intake to the top of the of the engine rail where the seal goes. If the gap is 75% of the thickness of the seal,then use the seal ends only. If the gap is less than 75% of the thickness of the seal, then use RTV only. If the gap is greater than 75% of the thickness of the seal, then use the end seals with a bead of RTV on top.