Still don't understand why you need so much pressure in them?
My '69 Satellite ran 30 to 40 psi for a nice little lift, and it did not ruin the ride.
Have put them on other people's cars, same 30 - 40 psi gave desired results.
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Now if you go with the Gabriel Hijackers with the outter cans for the bags, you can put more pressure in those.
But they have a terrible ride to them at any pressure, like rock hard feel every bump in the road.
That's why we quit using the Hijackers and went with the Monroe-Max, night and day difference in ride quality and only needed minimal pressure for desired results.
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You have too big of a tire on your Duster, and Dusters have huge wheel openings compared to the Darts.
So if you are rubbing a Duster, sure sign too much tire. (or you need more offset on your wheel to push it in closer to the leaf springs.)
Now if someone (like many have done) put a B Body 8 3/4 under your Duster, then your rear end is wider than the stock width A Body 8 3/4, and in turn is pushing your wheels and tires out closer to the quarter panels.
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