Just a little history on the 637. When it was first introduced, the engine wouldn't last until it got to the dealer. There was a stop production order and it took 4-6 months to find the cause. Seems that someone in the setup of the machinery for production of the engine block changed the size of one hole in the oil pump area and caused a 100% failure of the engines. I remember sold trucks that we couldn't repair for months and, believe me, the customers weren't easy to deal with both at the time and the next time they wanted to buy a new truck.
