The u-joints can all be lubed. They might not have a Zerk fitting but they should have the hole with a slotted plug in it. Take the plug out, put a Zerk in, fill them up, and put the plug back in. Inspect the seals and seams closely for rust or looseness. If you do find a bad one, just replace the one. I found that the new aftermarket joints were looser than old Nissan joints.