You have the larger sized diff that was available on the V8's of that era. If you check, you'll probably find that the screws that secure the bolt flange are 12 mm and not the 10mm screws that the SDL originally had.

What's curious to me is the claimed ratio of 3.07. AFAIK, all the gassers of that era, with the exception of the 300SE, had the 2.47 diff. The SE had the 3.46 diff.

If the diff is what I believe it is, any axle that came from one of the V-8's would work.

BTW, the bolts on the outside of the housing don't secure the axle or the stub shaft. There are still internal clips for that task.