The NA front upper control arm contains a ball joint that was not designed to be replaceable. Moog to the rescue! This replacement unit will let you change a worn upper ball joint without having to change the whole arm. It's pressed in and includes a snap ring to hold it in place. We've seen other replacement ball joints that would pop back out again unless they were tack-welded into place, but not this one.
You can tell if your upper ball joint is bad if you get a hard thump under braking or sudden cornering loads. Also, the ball joint should have some resistance to movement and not just flop around. Failure usually starts with a damaged boot that allows debris into the joint.
Be sure to pick up the boot installation tool as well - it's easy to cut the boot if you use a socket, and it's surprisingly hard to press the boot into place.
Cars that use NA uprights should use an NA ball joint. Cars with NB uprights will need an arm with an NB ball joint - so don't think about using this for your NB.