One interesting one was their 076-0019 & 20 front calipers which show as
fitting various non-ABS 505/604 including the N9Tx and 78-81 Audi 5000.
Their 071-5813 caliper kit fits the above and also various Porsche 924 and
944.
This suggests that caliper upgrade intended for Audi or Porsche might fit
the 505. Certainly, the Audi 5000 one would bolt right up.