I've been doing maintenance on this truck. Had a tapping noise in the valves. Sounded like it was coming from cylinder #2. So it needed some new seals and gaskets as well.

I tore it down to get the valve covers and rocker assys off and replaced all 12 hydraulic valve adjusters. Put the engine back together and I still have the tapping (fairly loud before and after the new adjusters).

The parts all seem to be intact. Nothing broken I could see The engine was still pulling good. My next step will be to run a compression check and leak down test. Don't want to chase this problem further without knowing that it has decent compression. Burns no oil.

Any other comments or ideas?

Pretty sure you should start looking toward worn rocker arms or shafts, or valve stem guides. The guide seals may still be holding out, but the guides 'could' still be worn. And, the 6G72 was never really a quiet engine.

You may be right there rxinhed. The noise has come back to the same area (cylinder #2 area) so I will take a harder look at the rockers and rocker shafts. There is so much hardware you have to take off this engine to get in there is what I hate the most. I have not verified good compression yet. May get to that today if I can get my shop warmed up a bit. At 72 yrs I don't like the cold much. Thanks for reading my post and commenting. Good suggestions!

Has it sat for any longer period of time? There is a process for getting the oil back into the VLAs. When they drain out, it will make a clackity tick.