I know everyone will say "I thought that was what it was" but
I actually thought that. The only reason was the angle of the cut on the bottom of the box tubing. When I mounted my filter mount on the same cross member you did it tilted forward and I had to cut it at an angle to make it stand straight up. That cross member lays forward.
The mount looks very cool
The only other bolt center I could come up that could require nuts welded in with that thread type and size was the rear trans mount.
good work!!!