Your year fintail has mirrors mounted on the doors. Cutoff for fender mount was the end of '63.

There are no bolt holes existing?

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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