Are you sure the leak is from the primary and not the transmission? Common leak point is the shifter shaft seal on the transmission. HD Part number: 12045

 

The inner primary bearing race should be .1" from the end of the main drive gear.

 

Just a couple of thoughts.

Agree with LQQK_OUT; must be sure that the IPB seal is the source of the leak. If the leak exhibits after a ride but stops after leaving a spot on the garage floor the size of a half dollar, the IPB seal is the prime suspect. If the trans is leaking, the leak will not stop until the trans fluid level is below the leaking seal be it the shifter shaft seal, quad seal, the main shaft/fifth gear seal or the large MDG seal. I have also seen the set screw that stops the shift fork seal leak as well. For this reason it is always a good idea to replace all the seals behind the inner primary when replacing any seal. You can see the shift shaft seal and shift fork leaks in the picture above and the picture below shows an IPB race that has walked into the main shaft/fifth gear seal. As Mark pointed out, there should be a gap where the arrow is pointing. It was fairly common in the early models for the IPB race to walk in to the main shaft/fifth gear seal which resulted in a trans fluid leak. Could very well be that is the source of your leak. If I knew how, I would delete the last picture; it was supposed to be an installed IPB showing the gap.

If you are not protecting the new IPB seal from the main shaft splines when installing the inner primary, it is very easy to nick the new seal and it will leak immediately.

 

Sounds like you got the quarantine special!

 

???????? This post is only 15 months old. Hopefully, the OP stopped the leak a long time ago.