Missing towbar clamp/spreader plates - help!

[catweazle]

I've just had a second-hand towbar delivered for my '92 Surf from someone breaking a Surf. I downloaded various different installation instructions as the bar does not appear to have a make on it (it is a round bar one) but all of them show a clamp or spreader plate that I do not appear to have. Does this matter? Also, there are no bushes for the long bolt at the back of the long side arms.

Will I be able to fit the towbar or have bought a duff'en?