We've streamlined the process and revised the design of the K Series Ultra Fuel (350 - 05 - 7000) to replace the Ultra Fuel Rails listed below. The Skunk2 Racing K Fuel Rail is the perfect compliment to the Ultra Street Manifold and especially the Ultra Race Intake Manifold with its dual injector positions. This K - Series Fuel Rail is used for both the primary injector position and the secondary injector position. One rail, two positions.