I have been trying to find out what OE W123 AC hoses were made from also. Per https://en.m.wikipedia.org/wiki/Butyl_rubber#Uses butyl rubber was not mentioned as being used for AC hoses so you may be safe.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked