"Proxy" wrote in message
...

damage except for impeller that I have written off anyway for this
experiment.

Ah, Ok, I didn't realize that you wrote off the impeller (I missed that)
(but the rubber smell could be the impeller galling up down there)

So, you didn't say anything about the U-joints. And when
mechanic dude said the yoke "isn't right", whats that mean?
Wrong one, wrong size, or bad, or what?

have you peaked inside the outdrive? bled a little bit of
grear juice out the bottom of the lower unit to look for
shavings? You replaced the coupler, or said that there
is no visable damage, or difference between that one,
and the one that was given to you, so I can't see that
being the problem. Besides, think about it, there is
nothing really to rattle there - the spline is a very percision
fit, and nothing really to rattle. Things that can rattle a
connecting rods, pistons, U-joints, yokes, bevel gears etc.
Could they have missed the shift-shaft lever alignment when
putting the outdive on? - dog clutch caught between gears?
Its all a pretty solid chunk of metal down there, so noise
can be transmitting from anywhere.

Hate to be stupid here, but are you SURE its not the motor?
i.e. since your not worried about water, cooling, impellers,
can you pop the outdrive off, and try to run the motor wihtout
the outdrive ? And whats the gimbal bearing look like ?
The front input shaft bearing for the outdive unit itself ?

Keep us posted.