I have no experience with it, but.... A body lift separates your body from your frame thus increasing the leverage your body has against your frame. It will make your truck feel Topsy turvy and sloppy.
It makes your steering shaft to short, your bummers useless and possible wiring harness issues.
Your auto transmission should just have a straight rod from the bottom of the shiffter to the pawl actuator on the side of the tranny so lifting the body away might make the rod to short.
Youll have to search here about spacers, but body lift is not the way...
Good luck dude.