Well, I'm taking a 2-pronged approach....
Temporary : picked up a set of BMR adjustable uppers. As soon as I get the bushing install tool I ordered (more on that once I use it myself and confirm it is "Da Bomb".....but have it on good authority that this tool rocks!), I'll swap them. I'm HOPING the tool arrives this week. Since the ECU is out of my WRX right now (sending off for an upgrade to complement the downpipe I threw in this weekend....I'll have a little 280+ HP sleeper of a station wagon later this week
) I'm driving the SS anyways this week and have it out of storage.
Back to the arms....I don't like Poly all-around up there (due to binding issues), but view that as better than the "play" that is there now. I suspect the bushings are long gone....you can FEEL the axle shifting around
Longer term : take another set of stock uppers, and put spherical bushings in the frame end of them. Or if I can find the proper-sized spherical bushings for the frame end of the BMRs, I'll put them in those arms instead.
Mike : I can tell you (from personal experience on my SS and other SS's) that if pinion angle gets outside of a "range", it'll cause driveshaft vibration. And yes, pinion angle will change with ride height changes. I'm not sure if GM used different arms on cars with the same ride height (to account for production "slop" in the build) or if they used different upper arms only on different ride heights.
In my case, I have a driveshaft vibration right now only SOME of the time depending on how the axle has shifted in those loose upper arm bushings!
Onto "refurbing" the uppers : I think what Eric is referring to is replacing the bushings (both in the housing and in the arms) and them making sure the arms are structurally sound. You need to check both the bolt holes in the arms that go around the housing bushings, as well as the "ring" around the bushings on the frame end of the arms.
And check both carefully.....one of the local ROD members had the uppers on his SS (under 100K miles, but driven "hard" [img]smile.gif[/img] ) come apart by literally tearing completely apart in the ring around the frame side bushing