FWIW, I was trying to look this up and answer. I only have a Premier PS2 3V 0-8-0 and it doesn't have 2 rail capability nor a switch. So then some searching for common MTH engines with the criteria you listed 0-6-0 or 0-8-0 with 2R/3R switching so it has to be a Premier engine, and my first attempt fails 20-3452-1 O Scale Premier 0-6-0 USRA Steam Engine w/Proto-Sound 3.0 as an example isn't 2 rail either. In fact, even more searching, and while they made 0-6-0 USRA in PS2 and PS3, also scale wheels (-2), or high rail wheels (-1) they were still only 3 rail with no switch according to the manual.
Example search https://mthtrains.com/prod-sea...ge_ak=0.2&page=1
Searches for 0-8-0 with the same criteria (Premier, and more likely a later 2017 model) I'm still coming up with the fact they all seemed to be 3 rail and no switch and not insulated wheel sets to be run in 2 rail/ https://mthtrains.com/prod-sea..._product_line%3A3934
So to me, it might be better if you list an engine you are thinking of that is an 0-6-0 or 0-8-0 that has a 2 rail / 3 rail switch.
