Jesus Wept... Brother... I know its looks pretty grim right now... But while Hoping against Hope... I'm going to continue to hold out for the idea that the problem remains with that Goddamned Flex-Plate. If the FPs were more commonly available... you could throw another one on there and see if it makes any difference. Its so strange how easily the Engine Fires Right Up and does not appear to shudder and shake. So I was wondering if you could find a Thin Wooden Dowel and place it at different positions along the top edges of the head and along the sides underneath to listen and feel if any noise either increases or decrease directionally. The best way to Autopsy an Oil Filer is to Collect the Drained Oil in a few Opaque Containers like several Milk Jugs and the take a Third Jug and fill it up about three inches deep with some Fuel Kerosene sold by Harbor Freight for Campers and Old Timers still using Wick Lamps and then use a Telescoping Magnet to isolate any pieces of Piston Rings or any extraneous Ferrous Metals. Likewise by cutting the Oil Filter with a pair of Metal Shaping Shears and washing the inner filter wad with the kerosene, you can flush out Babbitt and small pieces of Aluminum and then open up each pleat for a more detailed washing and inspection. Swirl the stuff around and after shining a light through the sides you might spy some shiny reflections clinging inside the walls of the containers. After removing the empty metal cannister and paper innards... use a Fourth Milk Jug with a Large Coffee Filter draped over a slightly more narrow opening in the Jug and slowly pour the complete residue of the gooey, loose contents down through the Filter. Then use some Fresh Lamp Kerosene to wash it as clean as possible and get a very close look at what is left behind for even the slightest amount of powdery, flaky metal whatsoever... and eyeball that stuff up close and personal with a magnifying glass to see what is what. If the stuff is non-reactive magnetically...its a good bet to be Babbitt Material from either the large end of the Rods or from one or more of the Seven Main Bearing placements holding in the Crankshaft. And... If any serious metal deposits or broken parts and pieces are found: Well... You know how you can tell when its either very difficult, very expensive or very crazy to try to rebuild certain kinds of Engines? Have a Look at the following all too familiar "Seven Deadly Sins" related to the Repair or Rebuild necessary for GM Atlas LL8 4.2L Engine: (1) Way Too Technical, Complex and Fussy and "Way Too Much Hassle." (2) Way Too Expensive for Brand New and Required OEM New Parts. (3) Way Too "No Substitutes Allowed" for TTY Fasteners. (4) Way Too "Nobody Does This... Because Nobody Knows How Its Done." (5) Way Too Many Broken TBs, Envoys, Saabs and Raniers with Donor Motors (6) Way Too Much Easier to R&R in a Donor Motor once Prepped on a Stand. (7) Way Too Expensive to Buy and R&R the Motor using an OEM Crate Engine.