That is not good. I worry about towing a camper and 950 lb trailer and using 5th gear while traveling. I had rebuilt the NV4500 a couple years ago with a new main shaft and fifth gear. The gear while being fully splined was a bit looser on the mainshaft that I think it should have been. No doubt import parts. I hope I am not creating what you have there. Can you describe the use you put it through? And the symptoms causing removal? I am curious. And good luck on your rebuild. It sure looks like it was time.