The Killer Dowel Pin (KDP) is a little thing that some people tend to ignore, until you notice a BIG puddle of oil under the engine. That's when you see the big crack that the dowel pin leaves after it gets jammed between the cam gear and the gear housing. When this happens, the gear housing is usually the thing that breaks due to it being made out of soft aluminum.
First a little background on the problem. The "Killer Dowel Pin" is an alignment pin that keeps the gear housing in place. However the timing cover that goes in front is not designed to prevent the pin from falling out. The gear housing hole is machined just a little bit larger than the pin, and the pin is pressed in. Depending on the tolerances, the result is the pin walking out of the hole and dropping down on the camshaft gear below it. Since the camshaft gear turns counterclockwise, the pin gets jammed between the gear and the gear housing. Since the gear housing is nothing but soft aluminum, it takes the brunt of the damage. In order to replace the broken gear housing properly, you must remove the camshaft.
It has been reported that a new timing cover was designed and implemented in the 1998 model year. However the new covers were being implemented at the same time the old covers were being used up. The exact time in which the old covers were used up is unknown. The KDP problem has been reported on as late as the 1999 model year trucks.
