...the real reason the U-18 never took off was the FDL engine great engine new but after 15-20 years they would fail catastrophically to where it wasn't worth the investment to fix money wise
I thought it wasn't the 'catastrophic' that did them in, it was the use of a relatively thin-wall cast crankcase that couldn't be fixed cost-effectively when, not if, it cracked in a critical area. The engine might still be running, perhaps with a reduced number of active cylinders, just not salvageable for rebuilding.
See a different type of kludged fix on an FDL in relation to the Lac Megantic accident...
BTW: Exactly what was it about the "120 degree" EMD fix that reduced smoke? That can't be in relation to a thermostat setting (the coolant temperature shouldn't be below 160 or so or the oil never gets hot enough to lose its condensation water right) and I'd like to hear more technical detail.