EMD SD50 series official thread (covers all variations)

OK that was a bad example, but Santa Fe seemed to be pleased with the FP45.

Engineer Spike--
Re: "but Santa Fe seemed to be pleased with the FP45"

Then again, the Santa Fe was one of the railroads that DIDN'T impose a speed restriction on Amtrak's SDP40F units after their derailments. I think the Santa Fe, at least on their main line, had SUPER-good track: maybe they felt that because of this they could tolerate locomotives that other railroads thought might damage either themselves or the track if operated at high speeds. (I'm guessing, though.)

Alan, there have been other 6 axle passenger units which have been successful, such as EL/NJT U34, and the P30CH. Between my example of the FP45, and SDP40F, it still begs a few questions. One would be the wheelbase of the Flexicoil, vs. HT-C truck. Was the hollow bolster an issue? How about the above board water tanks? One theory was that sloshing water made them unstable.

I forgot to mention the SDP35, 40, and 45. I haven't heard of Seaboard, Southern Pacific, Union Pacific, nor GN/BN having any issue with them.