best way to replace shift shaft seal 901

[Jerry1]

Hi I have a 67 912 with a 902/1 transmission. I had a leak at the shift shaft so I removed the trans and removed the rear cover. The question I have is what is the best way to reseal the case. Is there anyway to reseal the middle piece with out removing the gear set. I have ordered the gasket for the end cover but not for the middle piece will the middle piece seal ok or must I remove the gear set and replace the gasket. Would you recommend a sealer or should it be installed dry.

Here is a picture.



Thanks for any input.