One of the optional features is a limited slip differential. So, they took the engine and fuel system out of a standard truck, and replaced it with a battery and a big electric motor. They didn't even do the obvious, and remove the drive train & transmission as well, and replace it all with 2 or 4 in-wheel motors.

Maybe it's cheaper that way. If you have to buy trucks elsewhere and modify them, they may not be sold without all the mechanical guts. Or at least not for a price that makes it worthwhile. Still, kindof a cop out. I always wonder where people get the money to do this stuff.