Just off the passenger side of the diff on the front of the tube, there should be some numbers stamped. Take an old tooth brush and cleaner and clean up the tube to read it. If you can't read the numbers, take some chaulk and scrape it into the number. Then wipe excess off. T
Do you still have the diff tag on the diff cover bolt?
The build number should start with a 6 IIRC and be 5-6 numbers long.
However, basically, all D44 front diffs and shafts will have the same requirement for the axle seal.