You can also remove the speedo pinion gear/adaptor and make a metal plate to cover the hole. They actualy make those plates. Then drive the car and see if the noise is still there. At the very least it would eliminate that possibility of the speedo cable gear assembly making the noise.
Yeah, I've written about doing that. Gets tiresome and messy, though - you lose fluid when you pull the speedo gear, then have to pump it back in the dang thing every time.
Nonetheless, that's what I'm doing next, followed by a replacement of the slip yoke and u-joints.
I figure those would need attention eventually anyways, so it's not a wasted effort to do so even if I wind up replacing the transmission. Worth a shot.
