
These arrived today and fit perfectly. Good shout, thanks!They expand into recess then screws push the jaws apart .

It absolutely is.The rebate in the photo looks to be the mounting slot .
No it isn’t , I provided a link to correct bracket which was confirmed as correct .It absolutely is.
And that bracket in the photo looks like the right one - the lever rotates a cam which locks it in place in the slot.
No it does not fit, it’s for completely different track .Totally different profiles.I'm not saying the one you linked to doesn't fit, just that the one in the OPs photo looks like the right one.
Or also works, if it matters to you so much.
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