Well it's all done. The x brake is fitted and works a treat. I can't believe they are not a standard fit. I replaced the seal and it was simple to do. Once the drum was stripped off it only took five minutes. The flange nut came off no problem with the air gun then the flange with the three leg puller. Fitting and setting up the disk brake was a doodle. My 90 is much quieter now and will hold on the brake no problem. At £250 it was not a cheap upgrade but I think worth every penny.
Winch is all fitted now as well so I am pretty happy with where it is now!!