One of the things that will need changed (if they are still on there) is the engine mounts on the frame.
Also, if it has a diff, it will be different.
Good info Carl I wrote the same two things in my reply but deleted them. The transmission crossmember will likely be different as well.
1968Beau The front crossmember on all of the frames has provisions for mounting different motor mounts. The same for the transmission crossmember location holes.