I don't have a 7720 near me to look at, but if it's anything like a 6600 I can help. On the outside of the "box" on a 6600 or 7700 there is a "X" brace made 3/4" (or close to that) round steel. I put a new radiator in my 6600 two years ago. I just tyed a rope on the X brace, hung a chain fall from the rafter's in the pole barn and it was easy. A old hay wagon pulled up to the right side of the combine makes a great work platform, not so far to the ground when taking it out also.

GET SOME HELP!!!!! THAT IS A TWO PERSON JOB!!!! BEEN THERE DONE THAT!!!!!