Bill:
Interesting question.
Here is a list of engines I quickly compiled from readily available sources. It may not be complete, but the results are interesting. Maybe someone else can fill in some blanks.
These are engines which were either photographed with pilot wedge plows of the type you describe or brackets, or partial brackets having been installed for that purpose.
K-27's- 453, 455(RGS), 461(RGS), 462, 463, 464.
K-28's- 470, 471, 472, 473, 475, 476, 477, 478, 479.
K-36's- 481, 482, 483, 484, 485, 486, 487, 488, 489.
K-37's- 493, 497, 498, 499.
I cannot find evidence of snowplow brackets on any engine not listed. Both 455 and 461 did not have snowplow brackets from what I have seen prior to service on the RGS, and never had D&RGW style brackets like 463 and 464 did. Again, that's just from a quick look. 474 apparently was the only K-28 not supplied with snowplow brackets.
The earliest picture I found of one of these plows was 1926, on a K-28. The K-28 plow had to be modified to allow space for the air pump. As passenger engines, they were counted on to keep the line cleared in normal circumstances, since they ran all over the line, both directions, every day.
I could not find evidence of snowplow brackets on #480 and several of the K-37's.
I have no idea where the plows were fabricated, my guess would be Burnham.
Mike