Injector replacement didn't solve my issue, thoughts?

[Hammerhead]

Well, this ghost has finally been caught.
If I hadn't put my truck on the dyno, I would have continuously changed parts in an attempt to solve this issue. In fact, I was about to remove the problem part and put it back on unknowingly!
As soon as the dyno operator put about 300hp of resistance at 1550rpm the knock appeared. The shop foreman and I instantly turned to the front of the motor where the sounds was originating from. Gotcha, Crankshaft Damper!
I just replaced the damper in July, so I wouldn't have even thought of it?
My front crank seal just recently started to leak, and it was one of the things I was going to change while I was chasing this issue. Yup, that means I would have pulled the problem part off, not known it, and put it back on! It made no noise, and doesn't leak when we pulled it off. Changed it out, fired up the truck, we never even took it off the dyno, and started putting the power to it...nice, smooth, steady power, and no more knocking sound.
I've listened to Camstyn's clip in this http://rawze.com/forums/showthread.php?tid=1408 thread he started, and I'm fairly confident that his sound is the exact same as mine. He did his damper a couple months before I did mine, so he's comin by the shop tomorrow and we're gonna put my old OEM one on his to confirm it (it was changed in July, but didn't make noise it was replaced because it was at 600k).