The oil pan is a factory European Passat part. Both B1s (VW Dasher/Passat) and B2s (VW Quantum/Santana/Passat & Audi 4000/80) got aluminum oil pans as options, I believe in the "GT" models.
I've seen 3 different variants: 1-piece and 2 different styles of 3-piece (the baffling was different between the two). They're all shaped, baffled and finned for longitudinal applications.
If trying to put the 1-piece into a VW Fox, the radiator gets in the way of the reservoir on that side. I tried to devise a way of raising the stock radiator up to help with clearance but that didn't work. The solution ended up being trading the 1-piece oil pan for a 3-piece, whose reservoir is smaller on that side.
I'll dig out some pictures of all the pans in the next few days. I've seen pictures online of a factory VW oil pan like mine, but designed for transverse applications. If I come across that on my hard drive, I'll post it too.
To stay marginally on-topic for this thread, the aluminum oil pans use the same bolts with the exception of 2, which have to be much longer.