Info Charlie from Rusty hope has sent me, as it might help others.............
My kits are a bolt-on for the ½ and ¾ tons. Some 1 tons use the same spindle as the ¾ ton which makes it easy. Some do not, which makes it less easy. If you measure the od of the spindle where the bearings ride and it is 1.375 inner and .75 outer your spindle is the same as a ¾ ton. You can bolt my kit onto the spindle and you are done. IF it is larger you can either replace them with ¾ tone spindles or machine them down to the dimensions of the ¾ ton spindle.