My nylatron washers lasted 70K with no maintainence at all, sounds like a lot of trouble re greasing the inserts of Polys every 6 months! Didn't bother when I rebushed the rear Di-deon on my Alfa 75 and Alfetta or the rear arms of the Grale. I wonder if the Poly bushes may be a bit harsh as well, I noticed a lot more road noise after doing the rear trailing arms on the Grale.
Whatever you do, retrack after fitting them, I thought just dropping the wishbones and popping in the washers would not matter, bald inner edges of the tyres 6 months later proved me wrong!
Which reminds me must do the tracking on the 155 after renewing the struts (I never learn
).