I love this discussion

So far the arguments for preservation are based on the locomotives “railroad” presence… but ignore the “holding” museum’s goals.

Museums, railroad or otherwise need collection policy statements and collections goals… base on the groups mission statement… (the preceding statement being made at the risk of being called elitist or seeing responses about the soul of railroading and the wants of volunteers over those of the management… etc…)

If a museum was trying to show the development of technology, including “modern” diesel technology” then one of these might work as a part of the collection. If you were collecting Union Pacific large engines, including for example a Big Boy, a Centennial, and a Turbine then the SD-90 could represent the next step… If a group were created to collect one of every significant EMD locomotive, it might work

Our museums don’t have the resources to collect one of everything. This is a basic truth. With that in mind, we need to make decisions and limit what we take on. For most of us a SD-90 won’t make the cut. For a few it may.

We need to ask ourselves why we hold and care for each piece in our collection.

That is why I appreciate our group. We have one goal, one piece of motive power.

So the original 90macs are going the way of many other engines - but there are still dozens of the downgraded 90mac43s. I think those would be the more worthy of the engines to preserve. It shows how something was adapted to work. (unless you want to start a rail museum based on failed designs) The 90mac43s still have the WOW factor for visitors. I can attest to that fact as they still impress me the few times we get them in our neck of the woods.

Now what about the older GE units? How many U-boats are preserved? How many -7s? Now we better start thinking about the -8s. NS retired their C39-8s, (with the exception of the C39-8Es) and they will probably find their way to South America. We are fast losing the motive power that helped GE become the locomotive super power it is today.

I'm not sure how many posters on this board had the opportunity to operate these engines, but maybe I can give some insight as a railroader, as opposed to someone on the end of a Pentax (I'm not trying to be condescending here, just relaying my own observations). The SD90/43 engines have arguably the quietest cab in the industry, and being isolated, is also fairly free of vibration. You notice this particularly when copying clearances and when trying to have a conversation across the cab. On the other hand the SD-60's left you with a tremendous headache and a hoarse voice from yelling after 200 miles. I had the opportunity to get a true SD90 and was looking forward to comparing it to its less powerful 90/43 sisters. Fact was I was disappointed. The amount of NVH on the engine was far worse than even the first AC4400's under load. It was as if the cab was rigidly attached at one end to the trucks and the other end to the air compressor. There was a lot of unxplained banging and crashing going on underfoot that could not be explained, in all not a pleasant experience, but certainly a memorable one. Perhaps the greatest downfall of the engines is the inability to cut out a single traction motor, if something goes wrong, then the entire truck must be cut out, which leads to a substancial reduction in haulage capacity. The AC4400s will simply reroute power away from the troblesome traction motor, and redistribute the power into all the remaining working traction motors, and often there is little or no discernable difference. My personal opinion is that both the AC4400 and SD90 will have short lifespans compared to the first and second generation EMD units, mainly due to their electrical complexity. I think the constant vibration will be the undoing of their electronics, only my guess though. Something tells me there will still be SD-40-2 units running long after both these classes are retired. I seem to remember reading somewhere that after the next world war, all that will be mobile will be cockroaches and Dodge darts, might want to add GP-9s and SD-40-2's to that list.

What is NVH

NVH= noise, vibration, and harshness.