I run AFCO 20231M's on my Duster. They're identical to the Mopar Oval track springs as near as I can figure, same rate, forward and rear section lengths, etc. AFCO stopped making them at the same time Mopar re-issued the Oval tracks, so they may actually be the same and are no longer distributed by AFCO due to licensing. That part is speculation, but all of the published specs between the 20231M's and the oval track's are the same.
I run them with 1/2" offset hangers which have the standard hanger length, the relocation of the axle backward is a pretty minor deal. I don't think it was a full 1/2" on my car. That's actually a bonus anyway, as it allows for taller tires. The original axle location forward of center, moving it back a smidge centers it up in the wheel opening. The 120 lb/in rate works well with a rear sway bar, which is what you'll want if your goal is a handling set up. I run 1.12" torsion bars up front, but I also run a larger, E-body rear sway bar. They should pair pretty well with the 1.03's and Bilstein's. XHD's are only 110 lb/in, which will be ok but probably on the light side for handling. The Hotchkis springs, as well as the springs Peter Bergman was having made, are 130 lb/in. And the Mopar XHD's have not gotten great reviews as of late, seems the ones made in Mexico tend to sag quite a bit. The Hotchkis springs seem to lower more than advertised, I know a few members have installed them and then gone away from them because they were too low. Not sure if Hotchkis addressed that or not. I would not run SS springs on a car set up for handling. Even if you run two from the same side so the ride height is equal the ride height is too high if handling is the goal.
Here's my car with the 120 lb/in AFCO's. I have spring sliders installed in this picture as well, so, the ride height is a little lower than it would be with regular shackles. It's less than 3/8" though, and since it's a 108" wheelbase car the ride height might be a little different than on a 111" anyway. You can see the axle location with regular length hangers isn't an issue. With the oval tracks keep in mind there's two versions, P4529414 which is a zero arch spring, and P4529415 which is a 1". I believe the AFCO's I run are zero arch, so keep that in mind when you're deciding on where your ride height will be. I also have a part number for the rear spring eye bushings you'll need, I'll look it up again.
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