2000 v6 accord, differential has something wrong jnside my differential. Thumping noise and vibration from 35 - 70. Fluid is getting dark rather quickly. Changed all parts associated. Now my question is do I need to rebuild the trans because the fluid is ****. I have stopped driving it. But I’m afraid the trans is going to start slipper once I put it back together. And wondering if anyone has had similar issues. And what was your solution to the problem. Transaxle is turning out to be a little harder to find then Expected.

 

Have verified it is not the inner tripod joint of either CV axle?
If the inner tripod joint bearing fails it causes the axle to be out of balance and alignment, which can lead to a thumping feel.

IIRC there was a carrier bearing issue with V6 Ody in the diff. These are same family of transmissions. Don't recall if it was a bad bearing issue or bad preload issue.

You will need to change the fluid at least 3x to properly remove most of the old fluid.
Drain, refill, drive the car around to engage all gears including neutral and reverse to push new fluid into control circuits.
It's more of a dilution til most of the fluid has been changed out.
3X fluid change minimum.
It should be mostly pink by then, if it's still a little dark, change it again.