It's very easy to do with you have moderate skills and tools.
Check out this video
Brothers kit makes it very easy.
You take 12" out of frame under bed and 8" off the end of the frame Weld frame yourself o have a muffler shop do it.
Have shop cut, weld and balance driveshaft 12" shorter
New rear brake lines, shorten fuel line. Etc.
https://m.youtube.com/watch?v=uSkcJsgCW68