Lotsa of good advice but nobody asked about the width of the rims, the tire pressure and/or the scrub radius. Never mind the shocks.
If the backspace of your non-stock wheels is not the same as the front space, ie; zero offset, like the factory front end was designed for, then the center of the tire's contact patch will not be in the right place relative to the Steering axis inclination; same goes for a tire height that is different from the stockers.
Definitions and Explanations of Suspension Alignment Terms
When this happens, the edges of the tires try to climb up every little rut ,cup or wagontrack in the road. And you perceive it as a constant nervousness. You can mitigate this with lots of tire pressure, but it never really goes away.
You have to fix this or live with the problem.
You can almost make your Duster drive like a SuperCar, you just need to know how. I won't say that my 68 Barracuda drives like a supercar, but it might have followed a newer Corvette for several hours at speeds of on/or about 120mph.
5* castor in an A-body, with zero to .5*neg camber, is very difficult to achieve , even with the Moog offset bushings. My guess is that your tail is a lil low to get that much. If so, then you gotta fix that first. The front has to be a lil down; I set my front ride-height in the center of the best part of the toe-change/bumpsteer pattern, and then adjusted the rear height to be about a half to 3/4inch higher as measured at the extreme ends of the rocker-panels.
Another thing is "bumpsteer" . I had to fix mine which took me hours and hours on an alignment rack. Mine was created by the 5* of castor at zero camber. I eventually dialed it back to 3.5@.5 neg camber. I eventually gave up a lil more camber for street use. which gave me back some castor. But required the bumpsteer to be revisited.
The point is that those angles are ALL inter-related and ALL tied to eachother. And there is no good reason to try to run a race alignment on the street.
BTW
There are a couple of ways to attack/adjust the infamous over-boosted/ numb feedback, of the Chrysler P/S box; and the parts involved are cheep. I now run a very small steering wheel, to make it even faster.Not a faster ratio; just less arm-motion. The factory Barracuda steering wheel is well suited to driving a school-bus; but not at all well suited to driving a street-bomber.
My car is a street-bomber, and a manual-trans; so I steer with the left hand and hang the heck on with the right,lol. I left enough boost in the steering system to make this a pleasant experience.
