There are 4 chains in that engine, absolutely ridiculous setup. If you are changing them all, you have to pull the engine to do it, 11.0 hours of labor. By the time you buy all the parts, you end up investing a lot of money in a 100,000 mile engine and dropping it back in. If you plan on keeping the truck for a while, do yourself a favor and just get a reman engine with a good warranty. If you don't plan on keeping it long let it rattle. As a professional, I probably shouldn't talk people out of doing repairs, but as a guy with a conscience I can't recommend spending that kind of money for a less than perfect result. Image dropping $1500 on this repair and then popping a head gasket next week...