On 09/06/2021 11:35, Murmansk wrote:
It's not riveted, the U shaped bit, it's been cut, as it were three sides of a square, then the metal on the still-attached side of the square bent to make what I referred to as a "tab" stopping the thing sliding through the hole.


A photo of the whole thing mounted on the towbar ball would
help. It's difficult to comprehend how that thing attaches
from the photo.