Well, I called GM customer care and was told that my 2017 2500HD is only covered up to 50K miles on the emission system. The "drive train", presumably the engine and transmission, are good up to 100K or 5 years.

After looking at the TSB that Cabletech had listed out (thanks Cabletech!), the bulletin addressed a Diesel Particulate Matter sensor- apparently not associated with the P140B code I was receiving. I do recall however, that my PCM was flashed better than a year earlier for a matter related to a DPF sensor and I was not charged for that re-flash (my service manager tossed that one in given the amount of $$$ I spent at this dealership over the previous years).

As to the P140B condition, GM won't budge. They state that all TSBs are "vehicle specific" and unless a specific component used in my particular truck is a known problem, they won't warranty the repair. They're holding firm to the 50K mile warranty limitation on the emission system. Which really SUCKS given that I'm now seeing multiple codes/indicators that are related to the emissions again. My take away: GM doesn't stand behind their product like they used to. But they'll gladly take your money for another new vehicle!

If anyone has additional thoughts, I'll welcome them. Seems like I'm getting no where with GM