When you get on the throttle does it sound like there's a pissed Leprechaun on speed whacking your floorboards with a shillelagh? If so you're probably hearing the sound of your driveshaft's U-joints binding and trying to send your pinion yoke into a thousand pieces. You've got axlewrap.
Axlewrap happens when torque and traction overcome the suspension's ability to keep the pinion of the axle from climbing (rear axle) or diving (front axle) under load. Factors that affect axlewrap and its severity include soft springs, tall lift blocks, stacked shims, rounded spring pads, and lots of power and/or traction.
Spring WrapIf your leaf springs are turning into big S's when you step on the gas, then you'll either need to step up to a stiffer spring or build some type of traction bar. Several off-the-shelf types work well and can be adapted into different vehicles, such as the one offered by Sam's Off Road. However, here are some tips if you want to build your own.
Non-Spring-Related WrapYou can get axlewrap even if your springs aren't turning into big S's. Some stock spring perches in vehicles with factory lift blocks are shaped like upside-down U's. The factory blocks are contoured to index the entire perch. If you remove these contoured blocks the spring won't make contact with the entire spring perch anymore. It's as if your springs are trying to support the vehicle on a seesaw.