When you first look at the main shaft, it may appear very daunting. But as long as you have a large workbench where you can lay everything out in order (and you have your Factory Service Manual handy) it's not really tough. This is actually two shafts. The main shaft has the input shaft at one end. You can see it being carefully removed in the photo to the right. The high-speed synchronizer ring may be loose on the end of the input shaft when you separate the shafts, be sure to keep the parts in order. We will come back to this later. On the end of the main shaft (where the input shaft had been) you will find a needle bearing. This is unlike the larger bearings you have already replaced because there are no ball bearings in it. This kind of bearing is for close quarters, looking more like a sleeve, it uses long cylindrical bearings that ride on a larger surface. Set this aside, keeping the components in a line to insure the right order of assembly. Remove the circlip, and pull the third gear, synchonizer low speed hub and needle bearing off all at once. You can keep them together to make it easier, but remember to replace the needle bearing with a new one from the rebuild kit. Set it face down on the workbench in its place in the order. Starting at the other end of the main shaft, carefully remove each bearing, and its set of gears and put them in line on the table. There are circlips along the way that retain each gear set, so don't force anything until you have checked for one of these suckers.