Grinding noise from rear when accelerating (with videos)

It was on the lift at Mitsubishi and I walked under it and saw nothing as well as the tech completely went around the car for like an hour shaking anything and everything to try and replicate the sound as if it was just a rattle... I know it's not, the circumstances under which the noise is heard, to me shows it's mechanical.. I had a tech ride with me and heard the noise but they put it in thr air and could not replicate the sound in the air.. My thinking is that it is the ayc because it had no load on the read dif so therefore it wasnt trying to transfer power around.. I took it to mitsubishi about 3 months ago because i was getting the service the awc light and the ran it and there was a tsb and they reprogramed it...But I recently filled it for the first time with about a quarter or a quart of mitsubishi Fluid... It was cold when I filled it to max and not running because I read that it is the way to do it.. I got frustrated today and with the car off but right after a hour long drive I topped it off to max again with about another quarter quart.. I will check it again tomorrow after my drive to nd from work and I also am getting a oil change tomorrow so I will inspect the drive train again tomorrow while it is in the air...Also I took the car yesterday to Mitsubishi and today I started the car and got a service engine soon light, it could be unrelated just the timing could be fluke but I will have my shop run the code tomorrow for sure