I also cleaned up the worst of the two rear shocks, after removing the link holding the remains of the rubbers and retainers used to secure it to the axle.
I came across a small imperfection on the casting of the Dayton shock, only to find out later that it was what remained of a hex bolt!
(last pic, just net to the hole) You can see on the pics that the big screw plug has also seen better days. I have been soaking both with penetrating fluid and hope to have a go at removing them in a few days.