What's the absolute maximum range of your Duster?

Absolute is relative as we know.
But I can get and honest 20 to 23 on the highway with the 16 gallon tank.
I run a stock 318, lock up 86 trans, Q jet and a 2.76 8 1/4 rear 215 70R15.
So it's around at least 300 miles for me.
My advice, as someone that has driven cross country, is don't run 70 on a long trip.
That will make a big difference.
Slow it down and stop for gas every 200 miles.
Be cautious.
You rear will probably need it anyway.