At least partial answers to Almo's questions:
There were 6 Car Body type K-M's built 3 DRGW, 3 SP. Then SP wanted a 'Geep' style of unit and that is what the last 6(May have been 9) were. Then there were the three that Alco built and they were a Road Switcher style of body. Exact number of units is foggy, that was a long time ago and I am not going to try and find a site at this hour. If I have the numbers wrong one of the fine folks here will be kind enough to make corrections; hopefully only with a candle and not a blowtorch.
As far as the rotary being wider than a boxcar, yes. Don't forget that they might well be plowing in snow deeper than they are tall or wide and therefore they have to cut a path that would clear any equipment. It might take several passes. Take a look at the front end of a plow and you wll see wings that can be extended to cut a wider swath. As far as the height issue, you let it cave in and come back at it again,I would guess. Andy