+1 with what you've been told. I send my BP stuff to a certain BF member up North, and swap in 130BCD stuff all the time.

The 7700 DA triple requires a middle ring that also mounts the granny ring. Unique to that crankset, and why I have one for sale. Most sellers of just the middle ring charge as much as a crankset.

However, with only one "shoulder," they make great SS cranksets.