>>10664570>>10664592It goes back to the fact EMD got the foot in the door of mainline diesel power at the best possible time, right before WWII. So they were required by the government to keep churning out FT's while everybody else could only make diesel switchers at best if they weren't making diesels for other applications (I.E. FM's opposed-piston designs went into a lot of navy vessels) or building steam engines for the raw power (I.E. ALCO building all 25 of the Union Pacific Big Boys between 1941-1944).
Then when the war ended, every other company in the market had to start with growing their mainline diesel road power against EMD which had gotten its shit together years before. Fairbanks-Morse, Lima, and Baldwin were the big ones that tried both cab and hood units but quickly taped out, and ALCO was the lone holdout until GE left them high and dry along with the 251 engine that just never got the time it needed to have the flaws worked out. EMD's GP7 was the death knell for ALCO as a result.
And then, with the locomotive market all but monopolized, railroads wanted out of the passenger game because the boom after the war was so short lived. So now the trains didn't even need to look fancy anymore. Once the need for steam generators was done away with on locomotives, the only real major visual change over time was the adoption of wide safety cabs or variations thereof. Function had become the sole requirement of locomotives, since freight clients didn't give a damn what the appearance was of the motor power that got it there. Ease of maintenance also plays a role - a lesson learned with the BL2 where the attempt at a cut-back F3 body shell just produced something that made it hard to access the internals (see pic). So really, modern engines all look the same because there really isn't much need for anything beyond the bare essentials anymore.
