Did you separate the two halves of the caliper? If it is an ATE, you're really not supposed to. Even when replacing the piston seals, you don't need to separate the halves.
If that is indeed what you did, you probably wont find those seals anywhere.

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63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6