What I ended up doing is buying a full set of urethane bushings which I can copy on the lathe for aluminum.
Now on to the squeaking..
I don't understand where the squeaking is coming from. The stock ones are sleeved with steel so it isn't between the bolt and the sleeve. It must be between the bushing and the spring.
Now this would be due to it moving inside the spring itself which means the outer bushing/spring eye fitment is to loose.