The 28's were built by ALCO. The 36's were built by Baldwin. Baldwin always made things cheaper. Not necessarily better, but cheaper. It is not known who did the actual design of the 28's. The decision to put the cab deck low drove the decision as to where to put the air compressor. There was simply no place to put it on the side of the engine where it would not block the fireman's view.
36's were built as freight hogs. Riding qualities at speed was not much of a concern. BLW built what they thought was the biggest thing they could comfortably put on 3' gauge rails. At the time they were the largest rigid frame 3' gauge locomotives in the world, and were only eclipsed by the D&RGW's homebuilt K37's, which pushed the envelope even further.
The riding qualities of the K36's are hampered by the very flexible, but much less stable Hodges trailing truck. The axle of which is located up against the front wall of the cab leaving nearly 10' of locomotive hanging off the rear. Any deflection the rear of the engine makes on even slightly substandard track is amplified by the time it gets to the back of the cab. That combined with the flexible trailing truck with little lateral stability makes the cab bounce vertically, and swing side to side. K36's also carry a smaller percentage of their engine weight on the pilot truck compared to a K-28, although both lead trucks are identical. More weight on drivers makes for a better pulling machine, but tends to be much less stable at speed. Another issue is the larger pistons and generally heavier rod assemblies of the K36's create a piston thrust issue that gets worse the faster you go, making the front end hunt. This is why K28's were allowed to run 45mph, and K-36's and K-37's were limited to 35mph.
Lastly - an opinion - ALCO built some odd looking machines. Baldwin made some losers in the esthetics department too, but ALCO built a lot more of them. I've found through the years that if an engine has an odd proportion or feature to it, chances are it was built by ALCO.
My feeling is the designers at the American Locomotive Company went to work for American Motors when ALCO quit building steam locomotives.
