Z the front frame

do i have to z the front frame on my 94 dually or is it something u gotta do for bigger wheels? i have helped bag a 96 crewcab on 22s before and we didnt z the frame and it layed out level but on some roads it would drag and some it would kiss the ground and just roll down the road like it wasnt layed out ??????????????

Only really need to z frame for a B/D but some people do it for other reasons such as big wheels but not needed on a bagged chevy

10-4 good buddy! thanks for ur help