Unfortunately I don't think there is going to be an answer that I like with this issue, but I figured I'd post up and get some thoughts/ideas on this. Just started the truck up and let it get up to operating temp. For some reason I had the 205 in neutral while it was running, as opposed to 2hi. Was checking under the vehicle for leaks, when it looked like the rear output was moving. Front was spinning (typical, parasitic drag, no front shaft) but the rear is bolted up to the driveshaft. I crawled under, sure enough, the output yoke is moving up and down. Looked at the nut that holds it to the output shaft, thats moving as well, so it's not loose. Pulled on the driveshaft with my weight, and it still moved. Held the front output and the rear still "wobbled". I can see the seal actually deflect as it makes its movement. Put it in 2hi, 4hi, or 4lo, and it doesn't move. For history, this is a case that was attached to a 4L80E which had a broken input shaft/adapter, and had bent the 205 input. I replaced the 205 input, since you could see that it was bent. With the wobbling in the rear output, I assume this means something else in the case I didn't replace is bent as well. Is it likely that it's the output shaft thats bent where the input fits? It's pretty rhythmic and slow in its wobbling. Can't see anything else that would affect the output shaft only.