Useful maximum tonnages for all of the locomotives, and the DE locomotives combined with a Slug.
Guide to Useful Tonnage for All Locomotives
If you just want the info, here are the numbers!
This is not the maximum each locomotive can pull, and it is not a tonnage that a locomotive can always pull. This is a general idea of how much tonnage this locomotive could haul effectively.
How I Got These Numbers
Each locomotive was loaded into a brand new sandbox session, with a number of nuclear fuel cars behind it. I ran from a predetermined spot at harbor military base, and took each train up the hill west of harbor. If the locomotive comes to a complete stop at any point of the test, it loses and I remove 1 car and start again.
Nuclear fuel cars with their cargo each weigh 87 Tons.
I started the run from this sign in the Harbor Military Base:
Starting from there, there is a very limited run-up before the grade starts. I think that this helps to account for situations where you do not have a long area to get going when pulling a load.
I ran each locomotive and would back off at the red line. I wanted to keep it relevant to actual hauling, where you would want to keep the temp under 105 to avoid too much damage.
If the train can get up the hill just outside of the harbor, it still has not passed the test. It must make it up the following gentle grade. The finish line is at the far end of the stone bridge.
I tested each locomotive with between 4 and 6 runs. All runs were done with some number of full nuclear fuel cars. The exception is the DE2 with Slug. It was able to clear the hill with 5 cars, but not make it all the way to the bridge without stopping. I tried again with 4 full cars and 1 empty, and it made it all the way. I think that the fudged 4.5 number better represents the upgrade over using the standard DE2.
Here are the full numbers: