Re: 99200

I'll take your word for it that 99200 lasted until 1951.
After the 1936 Como Roundhouse fire that burned off it's wood housing, #99200 was fitted with a steel sheathed body and a sloped back tender from a standard gauge Denver switch engine.
Following abandonment of the narrow gauge mainline in April 1937, #99200 was assigned to the last remaining section of the line, between Leadville and Climax.
Like all Rotary snowplows of it's era, #99200 was designed for use on either narrow gauge or standard gauge. After the line was Standard Gauged in 1943, #99200 was fitted with standard gauge wheelsets and used for a time afterward. It's demise was caused by a broken wheelshaft and scrapped. If you say that was 1951, I won't argue it. There are a few pictures that show 99200 in service with the new body and sloped back tender.
I have never heard any indication that it wasn't scrapped, I'd be very skeptical about that.