Weak rearend. And cost a lot to replace.
its not the rear end that is weak, its the mounting for it
there was a recall on the 04-05, and the kits to bolster the rear diff to prevent the issue are relatively inexpensive as far as I can tell.
parts are pretty cheap, as its alot of stock CTS and vette stuff.
I was drooling over how cheap 2000+ M5's have gotten, but jeez, the CTS is a little more, but with lower miles and way cheaper maintenace and better MPG it seems like an easy choice
