Hello All, thanks in advance for your expertise...
I have a 2008 Express 2500 6L V8 that just crossed the 100,000mi milestone. She runs great, have had no serious issues (other than what seems like a constant headlight replacement...). I took a look in my manual for scheduled maintenance to see when the timing chain was due for changing and it's not anywhere on the maint schedule (which goes up to 150,000 miles). Looking around the internet opinions vary greatly on the replacement of these chains, I've seen anywhere from 75,000 miles, to 300,000 to never... Similarly a couple calls to different shops got me different answers...
I would like you opinions. I'm of the mind that if nothing sounds or feels wrong, I shouldn't monkey around in there.

Followup question, is the chain like a belt, where if it goes it's a catastrophic failure, or can I recover from a chain failure?

 

I've never had a to replace a timing chain on any of my many GM vehicles. I consider them to be "lifetime of the engine". SBC motors are generally non-interference, so breaking a chain (I've never heard of it happening) would not be catastrophic. That is my unprofessional opinion, but I stand to be corrected.