Gerst Dominator Series 4 Link

Dart's have a 111" wheelbase, Dusters have a 108" wheelbase. So as Joe pointed out that's exactly the 3" difference. It's not the tank, it's just the wheelbase of the car.

I think he said there was 3" more room on the shorter wheelbase Duster, which doesn't make sense. That would be a head scratcher for me.