To rebuild your SY upper ball joints requires you to take a chisel and undo the Factory staking done to keep the upper housing that contains the plastic insert from coming undone. These can often be repaired and re-used but British Tool Works now has brand new stainless housings available for $75 ea.  These also incorporate a grease fitting unlike the originals.  Here's an idea - grease your ball joints!
This may also fit Early SZ's.  If your SZ has a big slot across the top, this insert does not fit.  This style of insert will be added soo.
A stainless zerk is included.