Case break on a 44 is 3 series, 3.73 to 2.54/whatever
4 series, 3.92 to 5.38
You can use 30 spline side gears in a 19 spline case and vise verse in a powerlock but not an open case. The carrier bearings are different between a 19 spline case and a 30 spline case.
If you haven't found one might contact R&P at 503-557-8911. Sometimes they have empty ones on the shelf.