I still think we are all hearing different things and labeling them differently.
1. "Normal" lifter tick at startup: a faint ticking for 5-10 seconds after the truck has sat for a long-ish time (usually more than overnight, although my old Frontier did this at every startup). I assume the oil runs back out of the lifters, maybe not completely, and it takes a bit for them to fill up again. I hear it on my truck and it doesnt bother me at all because of previous experience with other vehicles (see my 2001 Frontier)
2. God awful loud tick that is more of a knocking noise for 5 seconds or so - this will happen after "I started the truck to move it to other side of driveway then turned it off....the next time I started it up it sounded like it was going to explode". This seems "normal" for the Hemi even though Ive never heard it on any other engine. SRT filter (at least in my case) seems to have helped mine.
3. Broken exhaust manifold bolts - loud-ish ticking (although not as loud as #2 on this list) that seems to occur for a few minutes and/or until the engine warms up and "seals" the manifold to the block again.
4. Actual honest to goodness Hemi tick - upper end (?) ticking noise that occurs even when the engine is warm/hot. Louder than injectors (although our injectors seem loud to begin with), louder than #1 on the list but quieter than #2.
5. Piston slap - bottom end very slight knocking noise, especially when cold. Mine seems to do this even when warm/hot, but if it really is piston slap, it should not necessarily affect the life of the engine just based on what is really happening