Likely a point, Mr. Fan Railer.
However, If I correctly understand, these SD-70 engines were built and were used in freight service by a Class I prior to their sale to METRA. To my best knowledge, any such engines were C+C configured.
C+C engines used in passenger service could best be called "problematic" (remember E's and PA's were all A-1-A+A-1-A), and METRA was wise to call for de-motoring one axle on each truck. While ATSF, owing to their superior trackage, never had incidents with such with their fleet of SDP-45's, different story with those on "my MILW". While there are several photos in TRAINS with these engines leading, their "truck hunting" characteristics became evident, and they were quickly assigned as trailing units only, and post A-Day, to freight.
Nothing ever came to my attention regarding any such matters with those acquired by SP, GN, and SAL. If such made any difference, those were of the traditional "hood" design.
Now enter Amtrak and their debacle with such motive power. They ordered a fleet of 150 SD-40's and assigned them systemwide. They were AOK on the ATSF; elsewhere "mixed" with several roads having derailments arising from "hunting", and on all roads very bad lateral motion (know so first hand on the MILW where once I was on the head and the Engineer was not about to go authorized 70mph). Well that story ended with non-disclosures resulting in EMD taking those engines back as trade-ins on Amtrak's quite reliable F-40 fleet.
