I also figured out my engine's shimmy problem. Damn driver's mount ripped apart. I wonder if there are stronger mounts I can get. To be fair, I did get 3.8 mounts. Just because they fit don't mean they'll work is the lesson I learned today. I've always heard people having trouble with 350 Buick mounts tearing on the driver's side, but I've never been able to find ones that aren't the stock black rubber replacement ones. I compared the 350 mounts to the 3.8 mounts, the 350 did seem heftier, but it was more expensive at the time. I'll go with the 350 mounts next go around.
All of the Buick 3.8L guys use HRParts and stuff driver side mounts. The engine mounts is one of the first things to break of an Turbo Regal -the Buick design is bad. Back in the early 1990's we all had 1000lb ratcheting cargo straps hooked from the frame to the motor to keep it from coming off the frame during spooling/launching.