'63 Valiant wiper linkage bushings

Gday, I'm Down Under and have a USA built '63 Plymouth Valiant convertible.
It was imported from Ca many years ago.
The car has been making clacking noises under the dash ever since I put it on the road. Only does it on bumpy roads, but where I live they are mostly bumpy.

I think maybe wiper linkage bushings shot? But open to other suggestions. Assuming that I am correct, my next question is - where can I buy them please?
I see listings on Ebay USA, but they are for later models.
Any help appreciated - thank you.
Gary