I had a 1995 Lightning that I tipped the scales at 4300 pounds. The Gen 2 Lightning was around 4650 and according to this Link the 2010 weighs 4700 without the supercharger and goodies of the 1999 Lightning.

Obviously comparing regular cab short wheel base keeps the comparison consistent but it might also reduce the 700 pound claim considering it is harder to make a bed lighter compared to a Supercrew. Considering the all aluminum 5.0 is already available, I doubt that will be included in the claimed reduction.

If anyone has real world results for what a current generation regular cab SWB weighs, please post it because a 700 pound reduction would make the truck possibly lighter than a Dodge Challenger SRT8.