Just bought a 2014 GMC 2500 Duramax with z71 off road package 3 weeks ago, currently has a little over 2000 miles. Went huntin two days ago in a couple feet of snow and while crawling in 4lo up an old logging road I managed to twist the mounts on the front drive axle, destroyed the axle seal, broke the universal joints on the front drive line and cracked the transfer case. The truck just has so much torque at low rpm its unbelievable. Love the Duramax/Allison combo but I seemed to have found a weak spot GM didn't find during testing. The ifs as well as everything behind the t-case stayed true and held strong but the 4x4 components failed under very little stress and throttle input.
Duramax diesel and the Allison Transmission, heated/cooled seats and the diesel exhaust brake.
Stronger 4x4 components that can handle the huge amounts of torque the diesel produces.