I found that routing is key.
It is possible to get the cable in quite a straight line from
the cluster to the exit grommet through the fire wall. Much manipulation
of wiring loom is necessary to achieve this. Once a clear line is created,
some tying up and down is needed to stop the loom from putting future
pressure on the speedo cable.
On the engine side, allow it to sit in a natural pair of curves down to the diff.
