I have read several post on here suggesting you buy and keep in your truck an extra cam sensor.How do you know when one goes bad and how do you change it.Also what is a good price for one? I have seen a bunch of them on e-bay just thought I would find out what a good price is for one and buy one just in case.Also what is a good price on glow plugs for the 7.3 powerstroke. I see a lot of this stuff on e-bay and thought I would start getting some stuff that I might need in the future .I rather get them for a good price now when I do not need them.That way if I need them later on ASAP and there are none on e-bay I do not have to pay through the nose. Thanks Chip (NOVICOUPE)