I didn’t have a oil leak but a bearing problem and in the end I changed the differential half shafts for the later model which, indeed , has a fools proof designs wrt sealing . In my case the main reason fir the exchange was that the old double tracked bearing cannot be found anylonger.
But in your case you may also wanr to simply replace the seals , in this case there is a careful procedure to be followed with correct shimming , which has to be precise .