Fitted the guide tube by removing the front seal on the gearbox using a screwdriver - just rip it out
You then hammer/push the guide in (its an interference fit) using some wood to stop the guide tube deforming and later coming loose
There is an oil seal installed in the tube
I got my guide tube from here
http://www.machine7.com/product.php?xProd=11100" onclick="window.open(this.href);return false;
Release bearing (late type) from here
http://www.machine7.com/product.php?xProd=624&xSec=358" onclick="window.open(this.href);return false;
The heavy duty operating shaft and guide bushes from here
http://www.machine7.com/product.php?xProd=13246" onclick="window.open(this.href);return false;
Its well worth doing it properly - I had a catastrophic failure of the early release bearing which provoked the change and left us stranded after Busfest