I have the Grey Hound #4000 LC+ 2.0 Trainmaster Big Boy from a couple years back Lionel # 1932170.
I bought mine about 6 or so months back but have not seen any for sale since.
It runs fantastic on o31 and actually has much less overhang then I expected due to the articulating drivers. More overhang in the back then the front for sure.
Its my favorite locomotive. Whistle is amazing!
Brad