A good budget minded one is the Milwaukee 2763-22 M18 1/2" Inch Impact Wrench,can be had for under $400 and will loosen anything on a KJ.
I couldn't find the Milwaukee instock at any local stores. What do you think about this Dewalt that's instock at Lowes?
https://www.lowes.com/pd/DEWALT-20-...rdless-Impact-Wrench-with-1-Battery/999947862
Also this is the HF gun I was talking about.
https://i.imgur.com/gmbVdWT.png