Overload shocks on a Duster?

They are not a good replacement for a proper leaf spring. The shock mounts in these cars were not designed to carry the load weight of the vehicle. In more extreme cases, the mounts will flex and eventually fail. It is better to fix or modify the stock spring pack. A re-arch by a competent spring shop will restore some ride height without making the ride too stiff. Personally, I'd add a couple of additional leafs from a vehicle with similar length springs. As an alternative, Hotchkis does offer springs, AFCO and ESPY do as well. Beware of springs from other sources, as some are cheap Chinese steel that will sag much faster than a Tijuana boob job.