Hi J,
You should have found a shim on the engine side, directly under the cover.
This shim thickness determines your pre-load.
The outer races are 'clamped' in place by the covers when torqued.
The Haynes manual is quite good on this except for one critical detail.
When measuring your pre-load, you need to place a piece of suitable tube
between the hub and the inner shaft, in order to lock the planet gears.
Take a look at
http://www.betaboyz.myzen.co.uk/forum/index.php?topic=4277.140 which is
where I did the pre-tension on my VX box. It appears crude, but it really works.
Edit: To add, as per Eric's advice a while back, if you're just replacing the bearings, with
all other things the same, pre-load should not be necessary. But it's always a good thing to
do if there's any doubt. And assuming you've found the shim.
Nigel