Littermates

Whenever I see a '74, like this '74, I compare VINs to see how close they are to Ludwig.

 I've seen a pretty close one before but unfortunately didn't photograph or write down its VIN.

And once I saw a '74 for sale that was a day older than me.

But this is the closest yet: a mere 3,419 away from Ludwig on the assembly line, to the younger side. (Obscured VIN because who knows why, but people fret about such things.)

Let's do a little math: there were 224,993 buses built between 1 August 1973 and 31 July 1974, for the 1974 model year. Excluding weekends and holidays there were 252 working days during that time, so we can figure they built about 893 buses a day. Meaning this bus is probably about four days younger than Ludwig. It's reasonable then, I think, to suppose that they were acquainted, or were at least within sight of each other, and possibly came over on the same boat, depending on this bus's destination code (Ludwig, a UF, immigrated via San Francisco).

The owner told me he has a friend who'd owned one-off VIN buses.