just pick up a 10mm and 12mm wratcheting wrench and youll be fine on the 617s. it makes the job soo much easier. for the 603s i changed out all 6 GPs w a 1/4in wratchet, 6in extension, universal joint and a 10mm and 12mm socket. no need to remove the intake or any injector lines. youll have a much easier time w those tools and youll do the job in half the time