Hi all, I had an email earlier this week asking if I had ever fixed this problem and I realized I hadn't posted my findings in case anyone else had a similar problem. Anyways, I did finally fix the noise on my truck just last week. The intermittent noise I was experiencing was due to wear on the rocker assembly. The underside of one of the rocker rods (that the arms rotate on) was extremely worn, but was not worn on the topside. So I could not see the wear by sliding the arms with the assembly still attached. Once I removed the rocker assembly and disassembled it, it was clear this was the problem. Unfortunately I shortly thereafter developed a valve that was sticking open which produced a similar noise that was not intermittent. Once I fixed the valve and put a refurbished rocker assembly in there, all is well.