The torsion keys put the lower in a bigger bind......the keys basically over crank your bars, but joints in a bind, thus making them wear out considerably faster.
Upper Joints are non-replaceable.....a new arm is needed. The upper joints are built into the arm.....non-replaceable. Moog upper arms are the only ones I know of that have replaceable joints.
Lower Joints are replaceable. Press fit.
Minus that front CV shaft.....this pic is JUST like a 2wd edge.(moog upper and lowers in pic)
U asked for this(don't think it shows much)(pic ripped from Alon's 2wd EDGE)