Dana 44 gears, would they fit in pretty much any differential housing?

You're banging the wrong tree. Dana 44 sets won't fit a ford unless it came with a Dana. Besides, if you have a "true" Ford 9" rear end, why screw with it? Did you find out why the axle failed? Maybe just tear it down, replace seals and bearings, set the gaps, fill it up with a SYNTHETIC gear oil (80W95) and go for it. I've rebuilt Dana's before and their pretty much unbreakable if you set 'em up right.