Is CT saving a PHI for a museum, or are the retired ones stored serviceable and available for sale? Perhaps, when they have enough for a good package, Metra might buy them to go with the ex-Surfiner Amtrak units they got. Or are those problem children in Chicago now?

The SD70 rebuilds for Metra work in their particular cash-strapped situation. But if you get federal and especially state money in California you have to buy the Latest And Greatest (for emission control). Which means the Chargers. And if you need large numbers (as Amtrak does, to replace a fleet that's old enough for museum service), Siemens is the only game in town that can deliver new passenger locomotives in quantity. I don't think Alstom is building diesels other than that short run of dual-powers for NJT. Who else?

What you've got on the passenger side is one big buyer and a few states, all of whom have mostly one-make fleets bought at around the same time, so they age out at about the same time and need replacement en masse. There's little ongoing business to make Wabtec or Progress interested in maintaining a passenger model or space in their production lines to build one. So the maintenance people, Amtrak, Caltrans, or otherwise, just need to learn how to keep them running, and possibly there needs to be a look at particularly unusual systems (Hydraulic cooling fan? How many of those are around otherwise? How often do they actually fail compared to "normal" electric gear?).

ISTR the F59PHIs had their problems at first, too. I rode my share of San Joaquins that were led by a BNSF freight locomotive with the F59 only serving the HEP load (did the CT F59PHIs have a separate HEP generator?). And usually not wildly late even with that kind of lashup. Since then, they seem to have settled into basic functionality.