Which Truck Head is the lightest in the industry?

Hi,

The trucks he speaks of actually weigh 15,788lbs. Why? Because I bought one off Davis. They are the lightest trucks on the market with a descent sized sleeper, other than Volvos. The 430 and 630 volvos can be in the High 14s on weight.

 

So seriously, what can be done to lighten up the truck? I have a 2005 Freightliner Columbia and can haul 46K with it and a reefer. My 1996 KW T600 can only handle 41K with the same trailer. How much of a difference would aluminum/singles make (it has steel wheels now)? I have to haul some heavy stuff and it's just killing me. T600 has Detroit S60 in it and I'm very happy with the fuel mileage at 6.3 mpg fully loaded. It's the weight capacity that's the issue.