I removed my fans recently and noticed the rubbers at the attachment points were toast. I managed to source some replacements that are 95% perfect. Aeroflow make an oil cooler mounting rubber kit 6.5mm ID that comes with 4 rubbers and inner metal pieces. The inner metal pieces are exactly the same size as the originals. The rubber OD is very slightly too large but not enough to be a problem I think. I have attached images of the finished product and you can just see a slight ovality. However, they screwed down just fine onto the radiator.
These are the parts I used. For reference I have an old one (which is shrunk and hardened) alongside a new one.
I remember a while ago that I sourced them from either Repco or Supercheap and they were made by Champion. It was a direct replacement in a blister pack. I will email Champion to see if they still have them.