EMD GP35 no. 2500 (builder no. 29595) was acquired new in December 1964.
In January 1965 it was renumber to 2501. Why in the heck would they
simply renumber it a year later? I asked this question to a long
time employee of the Alaska Railroad and was told, "The story I got was
that back in the days when the train number was diplayed in the number
box (e.g. X2500) the roundhouse kept running out of zeros. The 3000
was also renumbered (to 3006) at that time. It seems to me buying more
zeros would have been easier, but that was the story. The scheme
we use now (lately for cars as well) makes sense to me. Under
it, 2500 designates the class, and each unit in the class has its sequential
number, 1 to whatever."