Excuse my camera "work", I needed three hands. Rattle is intermittent and only happens at idle speed when the engine is at operating temperature. NEVER rattles at start up, or at the known 2500-3000 RPM range under load indicating timing chain guide issues. New rear hydraulic tensioner has been primed and installed with the OE Ford (7U3Z6K254A) replacement. I've read it could possibly be cam follower/lifter noise, but that sounds more rhythmic with a sharper ticking sound from the videos I've heard. I understand removing the valve cover is the only way to be sure, I just want to have an idea what to expect when I open it up. Stethoscope probe is touching the rear of the valve cover with one ear piece against the built in microphone on the camera beginning at 32 seconds. ST has 78,000 miles, is driven very gently using only NAPA full synthetic (Valvoline Synpower) 5W-30, and FL-820S filters replaced at less than 4000 mile intervals since I drive less than that every year. Thanks in advance, I'm hoping for the best and wasn't planning on my 5.0L V8 (302) conversion this early.