Any they were made from 1982 - 2004, however a 2WD with dual piston brakes would be the best score, these are the 1998 - 2004. You can also look for the 1978 - 1987 G-body cars (regal, monte carlo, malibu, cutlas, gran national, grand prix, el camino, etc.)
If you want aftermarket, you can get A-arms from Global West, UB Machine and a few others that make road racing parts for the G-bodys. (although insist on the correct units from Global West as they did have a jig problem a while back). I recommend tubular uppers with your plan to lower it, especially if you are using air bags as well. Summit offers the lowest price on drop spindles at $105. S-10 warehouse on Ebay has dual piston brakes and spindles for $300
Scott
