I really want to know what changes were made to fix the problem. My 98 Trep has been great. Had the valve covers off last year and there was no sludge. I do have the exhaust valve seal issue now at 91,000 miles. I'm going to fix it soon and I want to replace the chains, guides, tensioner, water pump, oil pump and what ever else I can think of. The new windage tray and oil pick up tube is on the list also. If we can find out all the changes that were made through the years we could incorporate them into our repairs. Its a shame they stopped making them. I would buy another.