1"3/8 " input shaft guy from southbend says most of these nv5600 that they see breaking input shafts are while under heavy loads higher rpms and high gear like in 6 or overdrive what ever you wanna call it which makes sense to me as I was in 6th pulling a loaded gooseneck trailer up a small grade doing 67 mph sucks to find out I'm really just a bad driver and I could've avoided this whole situation but this kinda catrastphry is not very common from what I understand