The linkage ball joints on the 123 Series diesels are all metal and are probably the same size as the newer plastic ones, so anyone looking to solve the problem permanently might just get the older ones from the junkyard.

If you insist on keeping the plastic ones here's a good tip. Since the plastic ones are almost certainly nylon plastic and the plasticizer (The chemical which makes a plastic flexible.) for nylon is water, you might just remove one of them at a time and place it in boiling water for a few minutes to replasticize the nylon. Five years later do it again.

Ben
www.reproduce100s.com