Well, happy to report the problem is fixed, although I have no idea what actually fixed the problem. Replaced the drive shaft, wear ring and put a new solas prop on. I made sure to align the wear ring in its proper spot and greased the inside so they could mate together properly. After it was all back together I fired it up and it sounds great. Still have to water test it but no more terrible screeching sound. I wish there would have been some clearer explanation as to which part actually fixed it but regardless, I'm ecstatic it's fixed and I didn't have to pay the local shop to do it. I can tell you the hardest part of this job is dealing with the rubber boot between the pto and the hull. I figured out that if you remove the clamps and then slip zip ties through the boot and pull them tight,(on 4 different side so as to try and keep the boot as round as possible) you can then have enough room to cut the small oetiker clamp to remove the drive shaft. Hope this helps anybody wanting to do this on their own.