I've got a '96 suburban with the 5.7 and I'm going to give it a tune up, but came across a question about plug wires. Does anyone know the difference between AC Delco part #'s 9718Q and 718Q (other than one is missing the '9'!). Also, Summit has their own brand that is less expensive. Being sold by Summit, I would have to think it's a quality product. Any reason not to go that route over AC Delco? Thanks!