I had a 94 Seville STS until November 1997. The car was a real money pit. I had problems with oil leaks, AC issues, electronic suspension issues, and a general feel the car was falling apart around me as it aged.
Finally, I traded the car just before it hit 70k miles. At that time, the AC evaporator leaked, the front electronic struts were throwing trouble codes, there was an oil leak in the "V" of the engine that couldn't be fixed without a major teardown, smelled of antifreeze and was just starting to get some white smoke out of the exhaust.
Email me privately if you would like more in-depth information about my experiences. I'd bet I have $7500 in receipts for the last year I owned the car.
On the other hand, I've owned several of the 3800 V6s, supercharged and not. Not one of them had any driveline-related problems. Four of the 3800 cars were sold with over 200k miles on them. Three that I know of are still plugging along.
Best of luck.
Sold: 1987 MB 300SDL, 320k miles, Astral Silver, Blue Leather, all books and records from day one.
Totalled: 1998 VW Jetta TDI, 488k miles, Classic Green/Gray Leather, loaded, E-Codes, "Slightly" modded, "Slightly" faster than stock, arrived 11/07/1997.
MBCA Member, Chicago Region