MILW U23Bs rode so rough were usually the middle units on the valley jobs between Chicago and Wausau between two GP38s. I believe these were the 4000s then renumbered to 5000s.

Amtrak SDP40Fs were so bad that on the firemens side would get such violent lateral they would literally throw you to the floor. On the engineers side you would have sore ribs from getting slamed against the window ledge on the right side of your body and the 26 brake valve onthe left side of your body. The 500-541 not as rough as the higher number 500s and the 600s. The 570s to me were the worst. Amtrak installed some sort of shock absorber/stabilizer later on which did improve the ride somewhat. These were the units that were so derailment prone.

My favorite locosfor ride quality were the E9s. There was nothing like leaving Columbus,WI on #5 or#3 widening onthe throttle and the faster you went the more they rode like ababy buggy. Whether on the firemans side or engineers sidethey rode great.

Rough ride-locos: U23B,SDP40F any ALCO RS model..Baldwins rode like lumber wagonsas did the six axle Fairbanks which liked to derail in crossovers.

Most older EMD power F7 FP7 and all GPs had a fairly decent ride quality.

Something ahs to be sad for the MILWs track. In the 60s it was pretty good as passenger speeds were still in the 90s and 100s and freight speeds were 60-70 mph. Of course I'm talking about what WE as crew members operated at not what the LEGAL speed was. Most MILW guys from officials to crew members were fast train movement guys. As track started to detierate in the 70s speeds were slowed but a lot of hoggers did not,IE derailments were HUGE! This may have had alot to do with ride quality on some locos.

I remember riding in the cab of one of the Amtrak 570s SDP40Fs on the BN between Minneapolis and StCloud,MN one day and was astonished at the difference in the ride from the MILW to the well maintained BN RoW!