The '73-and-up 44 axleshafts (above, top) are beefier than earlier ones, tempting some to swap them into '72-and-earlier housings. But does it work? The way we read the axleshaft specs in the Dana book indicates this might work with '70-'72 44s with bills of material 603170, 603351, and 603352. You'd probably need to swap everything from the knuckle out, too. We haven't actually done the swap, so you must check it out for yourself. This is just an example of how to track down the info.