Hello fellow members of rctech. I apologize if im posting in the wrong forum. I have a wheely king that i converted to the traxxas velineon vxl-3s brushless system. I have changed out the plastix gears to the hardened steel gears and put integy hop up axles front and rear. I can drive it with one drive shaft attached to the front or rear. But when i have both attached, the rear end makes a clicking sound. After unattching on the clicking sound is still there. Ive taken the axle apart and dont see any damage to the diff or axle shafts. Any suggestions on how to fix this problem and be able to drive with 4wd instead of 2wd?