Cowdog ,I can only tell you what I did. And it will stir a debate.... I asked the guy I trusted at the parts counter who was very knowledgeable about this same thing when I first bought the '05. He said it wasn't necessary to change it that often. I kept a look on the color of the fluid and only changed it once in the 4025 hrs I drove the '05. Right or Wrong it did fine. I also seldom use my dump so did not change it much at all. I only used it for checking the fluids. I stretch out the transmission change after broken in and after the last change was clean on the magnetic plug to almost 400 hrs- that is almost twice a year for me. I change the oil at 75 to a hundred and had great performance using the JD 15 w40 quality oil in it (because we have it in bulk) and always use SUDT in everything else including the knuckle cases- . bordercollie
edit: my 2011 manual says only filters need replacing every 200 and fluid every 400 on the transmission.There is a thread on this here too. but if I'm changing the filters ,I'm going to change the trans fluid too at least for now.