The front axle will handle 35's, Its the rear that can hit or miss. Do you know what rear axle you have? Dana 35(weaker axle) has a round plastic fill plug on the diff cover and the dana 44(stronger) has a square metal fill plug on the diff cover. You also need to think about upgrading a few other things like, steering, brakes etc. 4" is a bit on the short side for 35's, but with proper extended bump stops it can happen. Also you might need to consider a gear swap, depending on what stock gears you have.