If it is just the twin step that bolts to the towball then all you need is some m16 bolts of a suitable length (I’m sure someone will Be along with the imperial version to be period correct). I would guess about 75-100mm long but get your tape measure out. They are nothing special and are just extra long towball bolts. Length will depend on if you have a towball fitted or not.
I have the single version on my 110 bolted to the towball. Deliberately bent so it is not the furthest point back before someone comments about careless driving!
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