Just thought I would share my experience fixing the gear shift rail leak (finally).   I have an '80 Brat with the top mount starter.   I got sick and tired of smelling burning gear oil.  I did a bunch of searching on here and it has been discussed before but I couldn't really find anyone that followed up after they fixed it.  The big question seemed to be whether it could be done in the car or not.  In my experience, it could not.  I am at least fortunate enough to work at a transmission shop and right now we are sort of in the slow season.   Today I had enough free time to tackle this thing.  

 

The 4wd shift rail is the deal breaker that makes it necessary to remove the trans.  The top cover plate needs to be removed to access the rail, fork, and pin.  There is also a spring and check ball for the detent.   Once the pin is removed, the rail slides out of the fork and the little ball and spring come out also.  Try not to lose them.  Then, finally, you can remove the 4wd housing and change that little bastard o-ring on the gear shift rail.  

 

Hopefully someone else finds this useful.  Sorry there are no pictures, I was doing this between paying jobs as I had time, and it was my ride home.  

Do you have the # for the seal or is it something easily matched at the parts store?

Its just a generic o-ring.  I used to work at a transmission shop so we had quite the assortment.  So far its holding up ok.

I managed to get all the seals needed to reseal these from my local dealer. If there are parts manuals online you can check any year 4wd from 75-79 and it'll be the same seals. If I can locate my receipt or my parts manual I'll post the number.

Not for this part specifically, but two local Subaru dealers told me "can't get that, it's older than 1985". Do I need to give them a part number, or are some dealers better than others?