Pixl Sorry about you health. You are giving away nice stuff. I am pretty sure, person who will come to collect will not take it free, at least I would not take free.
Those U-bolts I have are 90mm wide and INOX made. Thread is 8mm metric. Clamps are made of well galvanized 3mm thick steel, I am pretty sure they will not rust fast.
I think if you post some pictures then it will be much easier to see what exactly you need. This bracket may be not only from STAB but also from other motors.
How to sell "Nothing"? That should be done in the dark room! Just ask “What do you see?” Answer, most likely, will be “Nothing!” So, take 2 kilos of it and deal is done! :)