Yes this seal is easy to replace. However its leaking is usually a symptom of something else going on. There is also an insert-bushing behind it that may be cracked. Make sure the transmission is not overfilled and that the vent tube is not kinked or otherwise clogged. This seal never sees enough action that it should wear out. For it to go bad is a sign the transmission has been over heating. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Mark McCulley
Sent: Monday, July 25, 2016 9:26 PM
To: vanagon@GERRY.VANAGON.COM
Subject: replacing transmission selector shaft seal

My '87 has transmission oil leaking from where the selector shaft enters the transmission case. Is it fairly straight forward to replace the seal with the transmission installed? This is a syncro if it makes a difference.
I see van-cafe has a write-up here:
http://www.van-cafe.com/home/van/page_131_783/transmission-selector-shaft-seal.html,
seems like it's not particularly difficult.

Thanks,
Mark
Seattle, WA