A new noise developed recently in my '87 'Burb. 170k, but well maintained, exc. oil press. When I crank 'er and let go of the key before it starts, or when I turn it off, it clunks/knocks just as the engine stops turning. This is hot or cold, no matter. I thought it was the flywheel to TC, but tight/rings. Rotated and checked FW to crank. Not engine mount, def internal. It makes this noise consistently. I now believe it's coming from the front/timing area? Any ideas? I wonder if I could post/link a short video w/sound?