It is definitely part of the backhoe subframe. I'm sure if you make the seller aware that it is part of the backhoe, he'll be fine with switching. The part number for the "support" is the same on the old style subframe as it is on the new style subframe so switching it out with the one on your new 2520 won't be a problem. You will still keep the same PTO shield pieces and the horizontal draft link pins. It's just that frame mentioned earlier that needs to be changed over. Upon installation, the mounting bolts should be tightened to 83 ft lbs.
I would definitely do the swap with both machines present.
I would definitely do the swap with both machines present.