Don't know if it's too late, but there is a group buy going on over at the impala SS forum for complete front end rebuild kits at $219:
http://www.proforged.com/1978-96-Impala-SS-Caprice-Front-End-Kit. This is for the kit w/ 9/16" Ball joints (which your Impala has).
If you are interested, I have a set of brand new lower control arms with the upgraded 5/8" Ball joints (discontinued, no longer available anywhere) installed. You would need to buy a set of spindles/knuckles for 5/8" balljoints (discontinued from GM). There are VERY FEW left , after that they are gone. They are currently being sold (liquidated I suspect) approx $65 per side (shopgmparts.co [/color]m) which is a FRACTION of what they were going for a few years ago. Hell I called the dealership here last month and they wanted $660 PER SIDE.
18021377 Knuckle, LH, 2nd des. for 5/8" stud
18021378 Knuckle, RH, 2nd des. for 5/8" stud
Order the front end kit with the 5/8 ball joint in that case:
http://www.proforged.com/1995-96-Caprice-9C1-Front-End-Kit, you will then have a spare set of 5/8 lower balljoints.
The 5/8 Ball Joint was used mid 95-96 on the 9C1 as a reliability upgrade. A very nice upgrade to do. You can read about it in detail
here.
The owner of Pro-Forged, Zack, is a really nice guy. I've used the pro-forged parts and they are superior to Moog. The "knurl" is better designed. There used to be pictures on the forum, but they got lost a while ago. The pro-forged parts have a 1M mile warranty. I have used several of their front-end kits and have never had an issue. The ones I put on the roadmaster in 05 are still going strong more than 100k km later.
If you are going to go through the trouble of changing the front control arms, then I recommend doing front springs at the same time. Moog 7628 or Moog 80098. If you can get a good price on GM parts, ACDelco 45H0184 or GM 88913497 PN (price is for a pair) will make the car feel like it lost 1000 lb and are a good match for the stock rear springs. They are stock Impala SS height but have a 750 in/lb rate. Click
here to see an installed pic, and pay attention to post #31, which gives you the proper way to install the coil and p/n for an upg. isolator. Slap on some
Bilstein shocks B46-
1104 front and B46-
0929 rear and you're set. I'm using them (springs AND shocks) on my b-cars and absolutely love them.
If you've never done so, replace the differential gasket with
Fel-Pro RDS 55028-1. The stock gasket did not have the proper oiling holes.
Good luck.