A quick and dirty trick I've used from time to time is to locate a bolt with
a 17mm head of the length that will clear.  Thread 2 nuts onto the bolt.
Use thread lock on them, and tighten them against one another.  Stick the
head of the bolt into the socket of the transmission, and use a wrench on
the inner nut to unscrew the socket.  Use the outer nut to tighten the
socket.  This way you are always working against the jamb nut.
Steve Sandlin
http://www.steveslockshop.com
'84 Wolfsburg Westy
'79 Transporter
'00 New Beetle