Other than the hardware they come with, they look the same to me. Same part number other than the suffix.
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It looks like you used the the flathead machiune screws which were intended for the countersunk inner pattern.
I think the only way this works is to use a allen heads or similar.
Hard to tell from the Speedway photo, but looks like that's the difference in the two kits.
You may have time to stop by a hardware store and buy four this afternoon. Just check the depth so there is enough threads to hold well but noit so long as to bottom out when tightened.
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