Very interesting, guys! Evan, I think you have a winner. It definitely matches the body style, size, 4-pin construction and keyway profile. Also judging by the hourglass-shaped plug guard in Squelch's picture that the Abus has about the same amount of rotation to the unlocked position, which is a match to mine.
I agree with Evan's logic that US manufacture isn't (or at least wasn't) a requirement, especially with Master DG's plastered with Made In Mexico
Glock (Austria), Beretta (Italy), Sig Sauer (Germany/Switzerland), HK (Germany) are examples of foreign companies that established a US presence in order to import their goods and win contracts. (Or at least pacify politicians and their districts to justify existing contracts). I imagine Abus could have done the same.
Also, I don't have any indication this lock is in widespread use either -- it rather seems like an oddball find.