there as a mechanic on the Acadia forum- that has his own shop- and also does work for a local GM dealers.
his shop also does trannies.
He said- that his shop- will replace the 3-5-R wave plate (BEFORE it breaks)-- for about $700 I believe.
He recommended folks whose vehicles are in the wave plate problem range-- to replace the parts BEFORE they break.
Better to pay $700 than $4000....
He was able to do the work without fully removing the trans (if NOT broken)...
if he wave plates broke- then it has to come out...
But in your case- you want to do a swap.
he posted how they do the work- by holding the engine from above using chains- and they remove the engine cradle from below-- and are able to drop the trans only...
theres a thread on it in the Acadia forum--- keydiesel was his name..
theres a few pics of an 08 Saturn they dropped the tranny on.. look under 2012 pics-- you can clearly see the engine in the bay-- no cradle- no trans.
https://www.facebook.com/Key-Diesel-and-Transmission-144710248932100/photos_stream?ref=page_internal