Update!!! This is semi bus related as it pertains to a Detroit Diesel filter head. My Excursion was having major problems. Found out it was the tube screens in the pick up tube were completely blocked. I did a modification to get rid of all screens in the pick up tube and place a pre pump filter on the frame before the lift pump. This serves two purposes. It saves the pump and saves the expensive $30 filter in the engine. I decided to use a Detroit diesel filter head so it is the same in the bus. Mods are done works great and runs like a spotted ape again. I found the filter head at Stewart and Stevenson off I-10 and 610 loop in Houston. Cost $48.
Here is one of the tube screens that has plagued the truck for so long.