Since day one sounds like a diesel (but it's not) when cold. Now has 34k. Sounds more like rods than valve train. Any TSB's on this?

There has been a lot of discussion on this for the last few years.
- Some people have gotten engines replaced.
- Some have gotten extended warranties.

Your biggest problem getting anything done is that the Helms manual states many times that noise lasting 1-2 minutes is normal. The simplest explanation is the design of the pistons, etc.
- Because the pistons are very 'short' they can 'rock' in the cylinder and produce a slapping noise. Some engines do it more than others. GM says not to worry about it. The engine will not suffer from this 'problem'. They may be right. I haven't heard of any catastophic engine failures related to this. Just kinda bothers me that a vehicle costing 40-50 thousand dollars will sound like a diesel. Mine does it. I just make it a point to let it warm up for a minute or two before I head out.