[rich1]

Here is an Experts opinion: Sean Hyland Mustang High-Performance Builders Guide 1994-2004 Cobra/Mach1 Reference info: .....The factory crankshaft damper, water pump pulley, and alternator pulley can be exchanged for underdrive units that reduce parasitic losses and reduce the speed of the accessories. This is especially helpful for the water pump, which can cavitate at higher RPM, reducing cooling efficiency. .... Many of the aftermarket underdrive pulley kits on the market reduce the effectiveness of the damper, resulting in increased harmonics and contributing to oil-pump-gear failures. Our newest design retains 92 percent of the original mass, reducing drag, but still providing adequate damping characteristics. The factory had a couple of different crankshaft bolts on the 4-valve over the years, and more than one torque specification. Since inadequate clamping load creates oil pump and crank gear problems, it's important to only use the black crank gear bolt (not the inferior silver one), replace the crank-gear-bolt every time it is removed, and torque it to 125 ft-lbs......

Like I said earlier...,aftermarket underdrive pulley oil pump failures can be caused by poor design / manufacturing or improper installation.