Class 5 set up issues...v2

I've had a look at my yacht and had a sudden brain wave. I should be able to fit a rear bike shock into the tube in front of the mast step. Where there is currently a bit of old rubber which presumably did a less effective job* to the one Im thinking about. If you follow the nose wheel tube back into the cock pit it terminates by being bolted through a cuff which is welded to a bar . I can cut this off put a U bracket there with some bearings and in the same way bolt it back together. Allowing the same system as AUS720 but with the shock in the mast step tube.

*I currently have this rubber dampening system bolted down tight as all the rubber is perished. It might be one of the reasons I get quite a of sail shake. Not knowing how this was originally set up means I don't know if it was bolted down or allowed to float? You can see it here:

Ahh... Thanks for that. Mine has a bolt that allows me to lock it up. Im now thinking for sailing on runways and such like. Do you know what your rubber shock was in its normal life?