Looks like it's time to upgrade to a 26 spline input shaft for my tr3650. This is what happens when your fluid is low or old. Pulled the transmission and drained it and I think only about a quart came out. I had a leaky rear main seal for awhile and assumed all drips on the floor were oil and not transmission fluid. What's weird is I had no signs of leaks anywhere on the transmission. Front and rear seals were clean and perfect no signs of leakage between the bellhousing, main case, and tail shaft. I have no idea where the trans fluid leaked from.
What you see in the pic is my damaged input shaft and what's left of the pocket bearing and thrust bearing that rides between the input shaft and main shaft. Low fluid, over 100k miles, sticky tires and driving hard, and this is what happens.