Does your Duster "float" at highway speed?

Yeah I don't drive mine above 70 becuase It gets a lil tooooo floaty. it's an old car. it's how it is.

Even when my dart was stock, it never floated, even at 115mph. A slant six car, was never too light in the front.

I had a 68 Charger that floated. The stock steering box had play that couldn’t be adjusted out. Make sure your box is tight.

This is a biggie as mentioned. Also, bushings are old and, more specifically, these cars are known to break out the location sleeve for the lower control arms.

Modern tires and shocks help a lot, and a full rebuild with better t bars will put it on rails and sacrifice virtually nothing as far as ride.