Full disclosure my truck is a1994 Chevrolet Silverado k3500. This is my first diesel. Experienced a cracked head. Replaced both with new heads from ssdiesel, great people, led to top end noise. Then replaced all the lifters and pushrods without removing heads, a challenge, top end noise still there. I have valve cover off now and don't see any obvious problem. Should I replace the plastic buttons? What should I look for. I saw one thread here where they had valve cover off without removing intake manifold, I would love to know that trick.