Massey 40 and MF54a backhoe attachment compatibility

I recently acquired an MF40 industrial tractor. I found an inexpensive backhoe attachment that I thought would mount directly to it, the MF54a backhoe attachment. It came off a MF50C. The mounting holes on the backhoe attachment and the tractor don't seem to match up. Can new holes be drilled or do they even have to? Am I missing a piece for these two to join properly? I thought that the backhoe attachment would mount right up to the tractor??