the old vanagon repair manual i have has this procedure:

speedometer cable, removeing/installing
work sequence
*removing
- disconnect battery ground strap
- disconntect speedometer cable     <from the speedometer, i guess>
- remove spare tire
- disconnect speedometer cable from EGR/O2 sensor mileage counter.
- remove nut from bracket  <looks to be just in front of the sway bar>
- remove circlip from speedometer cable  <on the grease/dust cap, on the
    outside of the wheel>
- remove speedometer cable from rubber sleeve in steering knuckle
    <just behind the tie rod connection>
- when installing cable, align marks on cable <at that bracket, in front
    of the sway bar>
- after installing circlip on speedometer cable end, seal with silcone seal

** caution **
to avoid premature cable failure, position cable so it is free of strain or
sharp bends. do not grease connection to speedometer, this could cause needle
to stick.

joel