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Not sure if its due to luck, coincidence or magnets but I've never seen a clamp that doesn't match those criteria. Clearly I'm missing something or not looking hard enough. I've a condor alloy post of unknown vintage in my parts bin that would be good to use in a pinch, and a ritchey comp (or logic, not sure) that could also be available, however if I must buy a new one (I can, but my #buyer spirit is at a low ebb) then I would go for a zipp service course. Probably.
If the clamping bolt(s) move(s) the two halves of the clamp together along an axis orthogonal to a plane bisecting both rails, you might not need new clamping parts. Anything else and you almost certainly will. Which post are you using/planning to use?