Why L.J Toy recommends a body lift at times..

A body lift of three inches is often necessary so your new "non-stock tires" will clear the front fender wells. Most suspension lifts along with larger diameter tire installations (no matter what height the suspension lift!), may not keep tires from rubbing.

After installing a suspension lift kit; front or rear axles still can reach full up-travel and hit the stock bump-stop. The tire-to-fender well clearance hasn’t increased, it remains the same under full compression as it was before your suspension lift installation.

Distance in the rest stance will be the same if not less on a suspension enhanced truck with new tires but, no body lift. It may be less because the more the axle articulates or droops to one side; the higher a tire goes into the fender well. This is just one side effect of big tires and a 3 to 4 inch suspension lift.

Also applies to Independent Front Suspension systems.

Is the suspension lift really enough?

As far as tire-to-fender well clearance is concerned, suspension lift height means nothing when the axle hits the bump stops. It's just showing you're left with stock tire clearance or less. And if your tires are 35 inches or larger, they will rub on the trailing edge of the front and leading edge of the rear fenders.
This is how a body lift becomes useful to move components out of the way. If all you do is a body lift, the center of gravity has changed; you’re top-heavy. Don’t blow a wad of cash on your toy then have to repair drivetrain components due to poor engineering.
This is just one reason you really need the designers and installers at L.J. ToY now. We don’t share our secrets; we sell them to each and every paying customer.