Even with the engine out of the truck, is a pretty big job changing out the gears. The harmonic balancer is a press fit and requires a tool to remove it. It also requires heat and or a press to install. The cam gear is also a press fit. They are tough to get off sometimes and the retainer plate is behind the gear and is easily damaged if you are not careful. To install a gear, the cam needs to be cold and the gear really hot ( 250 + degrees). This will let you get it together with out a big hammer. Just pressing them on cold will ruin the gear, it needs to expand and then squeeze back tight to the shaft.
Joe
