1.) Can you post picks and part#s of the output shaft you rec'd?
2.) Have you changed the lip seals on the output flange side covers?
If not I do that 1st before changing the flanges. Although yours are pitted there is not a lip seal burnish line showing any contact with the seal. My guess is they are shot. The since the Diff is a
oil bath and the resting
oil level is below the side cover seals, there is not a whole lot of pressure to cause a leak. But if someone filled the diff while only the rear of the car was jacked that would add to the leak rate.
Side cover oring
https://www.eeuroparts.com/Parts/324...g-33111214144/
Output shaft seal and snap ring
https://www.eeuroparts.com/Parts/168...ial-152941101/
3.) It looks like you have BDR axles spacers installed on your flanges as well. From your axle bolt spacing it appears your output flanges have a smaller bolt pattern when compared to the BDR spacer on the website.
https://www.iconicparts.com/axel-spacers
Can you dissemble the spacer and flange and get a On-center measurement? it would really help. compare yours to the Ebay link I posted below, there are 13 pics in that listing showing ALL the various measurements.
4.) On this used set you can see the wear line from the seal.
https://www.ebay.com/p/1422198240
5.)The flange PN should be 33131214102
https://www.ebay.com/p/1422198240?iid=163891704505
https://www.pelicanparts.com/More_In...-1-214-102-BOE
Last observation and its not a slam. Those output flanges are what I'd call severely pitted and appear to have been exposed to the elements (read that not installed in a diff that has
oil in it) for an extended period. Even the snap ring groove and splines are corroded.