See my previous post : Loose trans mainshaft. Car in question is 99 v6 AODE
'vert.

Well I was able to get under there and replace the bearing and seal today.
The whole job took about an hour. We had to turn down a seal puller 20
thousands to fit the old bearing and press it out (and press the new one
in).

The old bearing measured O.D. exactly what the new bearing measured, but the
old bearing was oblong when measured I.D. Not really enough to see with the
naked eye, but measurements varied by more than a few thousanths, proving
the bearing was very worn. There is far much less play in the mainshaft with
the slip-yoke installed now.

Everything was easily accessable to get the tail shaft housing off of the
trans with the trans still in the car, the bolts were all 13mm or 15mm,
6-point, except the pinion flange to driveshaft bolts, which are 12mm
12point.

The vibe is gone, and the clunking is 99% better. There is still some
clockwise-counterclockwise play, but enough that it is acceptabtle as
tolerances inside the transmission. Not bad for 10 bux.

Thanks to all for the input and help.

Carl