Problem solved, I hope, got my car back today after 3.5 days, one of the techs that over heard the conversation today confirmed my suspicions, I believe.Techs were unable to determin what caused this major issue.
( Issue being, they had to replace everything, clutch packs & all ) SAID IT MAY BE BAD PART FROM THE BUILD.
I had the lube & additive changed a short time ago because there was a bulitin on rear differental lube. Problem being, when they changed it theyforgot the additive and that what caused the chatter in the plates.
The tech that over heard us said they had lube back in shop which had additive added to it and some didn't, and LOOKS LIKE MINE DIDN'T.
I have an 06 and it must have the additive added when changed, change every 2 years, so be aware xlr owners. Master tech & gm concur.

Problem solved, I hope, got my car back today after 3.5 days, one of the techs that over heard the conversation today confirmed my suspicions, I believe.Techs were unable to determin what caused this major issue.
( Issue being, they had to replace everything, clutch packs & all ) SAID IT MAY BE BAD PART FROM THE BUILD.
I had the lube & additive changed a short time ago because there was a bulitin on rear differental lube. Problem being, when they changed it theyforgot the additive and that what caused the chatter in the plates.
The tech that over heard us said they had lube back in shop which had additive added to it and some didn't, and LOOKS LIKE MINE DIDN'T.
I have an 06 and it must have the additive added when changed, change every 2 years, so be aware xlr owners. Master tech & gm concur.
You say "change every two years"... does it have any mileage limits, as in "every two years or ???? miles?"

You say "change every two years"... does it have any mileage limits, as in "every two years or ???? miles?"

Tried to get more verification from gm today with little help, refered me back to dealer, problem being different dealers have different answers to this one.
So I think I will just go with what my dealer said on the two years. Sent an email to gm, see if I get an answer back them.