QUOTE(oldie914 @ Sep 25 2013, 01:21 AM)
Your axle flange with the 34mm spigot is a flange for a 1969 901 with an aluminum case The other one should be for a 1969-71 with a mag case.
Porsche made many changes in their axles, flanges and differentials from 1964-72.
During this period, they had 3 different methods for securing the differential gear shaft, 3 different axle shafts and about 7 or 8 different axle flanges.
They introduced the 110mm axles in the 1969 model year retained by 4 bolts and 2 roll pins. The 1969 transmission had an aluminum case like the 1968 model year so they produced new flanges to fit the new axles. The flanges had a 34mm spigot to fit into the differential and an overall length of 110mm.
In the middle of the 1969 model year, they changed the transmission to a mag case. The mag case differential was about 10mm longer, had bigger tapered roller bearings and a larger interior diameter for the axle flange hole. New flanges had a 35mm spigot and an overall length of 105mm. The flanges were shorter so the flange to flange spacing for the installed transmission would be the same as for the aluminum case transmissions. These flanges had part number 901 332 209 22 and were continued through the 1971 model year.
The 1972 model year had the 915 transmission. The 915 differental was longer than either of the 901 types so the 915 flanges had an overall length of 98 mm with a 35mm spigot.
The axle flange spigot is not a bearing surface; it floats inside the differential so I don't think you would have a problem using the flange with a 34mm spigot in a later differential carrier.
WOW! This sounds like the voice of authority. I hope you stick around and become an active member.