Dug out the MTH RK version of the M-10000 for a few laps around the pike this week:

I bought this thing some 25 years ago planning to give it to The Old Man as a Christmas gift. Of course, as so many things with MTH back in the day, it's production was hopelessly delayed...so long that The Old Man passed away before it hit the front porch. A bit of an experiment, really, to see which emotion of his outweighed the other...plastic construction vs. the toy train love of his life, the
Streamliners. I suspect he'd have said "That's pretty nice...too bad it's plastic" lol.
This is the LocoSounds version, so bell, horn, rudimentary diesel engine sound, but no station announcements or ProtoSound features (and most importantly, no battery). That was a dark time for me and MTH...nearly everything that came in was DOA. This one ran as intended, straight out of the box.
Lionel made a nice version of the M-10005 during the mid-1930s. It was pretty nice too:

He'd have liked this one...it was metal.