Has anyone successfully used the USCartool A500 Crossmember?

So I also ended up cutting out more of my original upper crossmember. So both of the inner mounting holes have been removed. Could have probably left the passenger side intact, but would have had to make some weird bends on the steel i'll be putting in, and to just keep things kind of symmetrical, I cut both sides the same.

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Looking good! What are the four holes in the floor for?