Purchased the latest model 20v Dewalt DCF889B impact which is rated at 400 ft. lbs. (older ones are 300 ft. lbs.). VERY easily removes and retightens all the lug nuts on my truck and trailer (150 ft. lbs). Always do final tightening with a torque wrench.
For the heck of it, used the Dewalt to install a new 2 5/16" ball (1 1/4" shank) on my WDH. The original ball was installed with a 750 ft. lb. impact gun to approx. 400 ft. lbs. Yes, the Dewalt DCF889B struggled to remove the old ball, but it did remove it. Nice to know I can use the DCF889B (in a pinch) to remove/tighten a 2 5/16" ball or adjust my WDH while I'm on the road.
FWIW, as a backup, I also carry a 24" 3/4" breaker bar with all the appropriate sockets to work on my truck, trailer, and WDH on the road if need be. I've found 1/2" breaker bars are too weak to properly service my WDH.
For those that need even more torque, the 20v Dewalt DCF899B impact wrench is rated at 700 ft. lbs (1,200 ft. lbs. breakaway).