This is easy enough to check. Take off the splash guard on the drivers side, grab the steering shaft, and give it a good twist. Any play should have corresponding play in the steering wheel. If there is any play on the lower end of the shaft where it meets the steering rack, it needs to be replaced.

In my case, I managed to bend my steering shaft... wheeling is hard on stuff lol.

As to OEM vs aftermarket, I got mine from 1AAuto and its been more than sufficient. There is a U joint in the lower portion of the shaft, which would be the main argument for going OEM. However, I have had pretty good luck with stuff from 1AAuto.