You should be able to weasel the naked trunions of the U-joint into the stub or outer axleshaft. Insert one of the U-joint caps into one of the ears. Make sure the needle bearings inside the cap do not fall down. The trick to getting the caps on without allowing the needle bearings to fall is to use the U-joint trunion to hold the needles in place while you seat the cap in the ear. Drive the cap down while holding the trunion in the cap (as shown) until you can see the recess that the C-clip fits in. You can now insert the C-clip.