Get the Milwaukee 2763 at Amazon -- http://www.amazon.com/gp/product/B00GFUA7FC/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00GFUA7FC&linkCode=as2&tag=reatoorev-20
Check out the full specs here -- http://www.milwaukeetool.com/power-tools/cordless/2763-22
This is my complete review, as well as many "action clips" of the M18 FUEL.
It successfully removed 2 different Honda crank bolts, removed a Subaru axle nut, removed a Honda ball joint, removed the 1 1/2" nut from trailer hitch ball, and drove 5/8" lag bolts into a railroad tie, an oak stump, and a live tree.
I used it exclusively in place of an air impact for over a week, and was not let down once. This impact has an unbelievable amount of power, and you will be amazed the first time you use it.
Milwaukee M18 Fuel 2763-22 High Torque 1/2" Impact Wrench