After the R12 -> R134 conversion, the condenser leaks; this is the (rare) model.
Ford OE Nr. 87BG19710AA
Forum Post: https://passionford.com/forum/ford-sierra-sapphire-rs500-cosworth/500641-sierra-a-c-condensor-needed-new-any-tips.html#post6815150
Klimaservice – Müller: https://www.klimaservice-mueller.de/
https://boodmo.com/catalog/part-condenser_air_conditioning-6041343/
KAGER 94-6273
PRASCO/AVA FD5255
KÜHLER SCHNEIDER 1820091